1.Refer to the exhibit. What will Router1 do when it receives the data frame shown? (Choose three.)
A. Router1 will strip off the source MAC address and replace it with the MAC address 0000.0c36.6965.
B. Router1 will strip off the source IP address and replace it with the IP address 192.168.40.1.
C. Router1 will strip off the destination MAC address and replace it with the MAC address 0000.0c07.4320.
D. Router1 will strip off the destination IP address and replace it with the IP address of 192.168.40.1.
E. Router1 will forward the data packet out interface FastEthernet0/1.
F. Router1 will forward the data packet out interface FastEthernet0/2
2. Refer to the exhibit. Which three statements correctly describe Network Device A? (Choose three.)
A. With a network wide mask of 255.255.255.128, each interface does not require an IP address.
B. With a network wide mask of 255.255.255.128, each interface does require an IP address on a unique IP subnet.
C. With a network wide mask of 255.255.255.0, must be a Layer 2 device for the PCs to communicate with each other.
D. With a network wide mask of 255.255.255.0, must be a Layer 3 device for the PCs to communicate with each other.
E. With a network wide mask of 255.255.254.0, each interface does not require an IP address.
3 .Which layer in the OSI reference model is responsible for determining the availability of the receiving program and checking to see if enough resources exist for that communication?
A. transport
B. network
C. presentation
D. session
E. application
4. Refer to the exhibit. Host A pings interface S0/0 on router 3. What is the TTL value for that ping?
A. 252
B. 253
C. 254
D. 255
Explanation/Reference:
From the CCNA ICND2 Exam book: “Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it throws away the packet. This prevents packets from rotating forever.” I want to make it clear that before the router forwards a packet, the TTL is still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL.
5. Which of the following describes the roles of devices in a WAN? (Choose three.)
A. A CSU/DSU terminates a digital local loop.
B. A modem terminates a digital local loop.
C. A CSU/DSU terminates an analog local loop.
D. A modem terminates an analog local loop.
E. A router is commonly considered a DTE device.
F. A router is commonly considered a DCE device.
6. Refer to the exhibit. Refer to the exhibit. After HostA pings HostB, which entry will be in the ARP cache of HostA to support this transmission?
A. (Correct Answer: A)
B.
C.
D.
Explanation/Reference:
A Explanation:
When a host needs to reach a device on another subnet, the ARP cache entry will be that of the Ethernet address of the local router (default gateway) for the physical MAC address. The destination IP address will not change, and will be that of the remote host (HostB).
7. A network administrator is verifying the configuration of a newly installed host by establishing an FTP connection to a remote server. What is the highest layer of the protocol stack that the network administrator is using for this operation?
A. application
B. presentation
C. session
D. transport
E. internet
F. data link
Explanation/Reference:
FTP belongs to Application layer and it is also the highest layer of the OSI model. Explanation/Reference
8. A network interface port has collision detection and carrier sensing enabled on a shared twisted pair
network. From this statement, what is known about the network interface port?
A. This is a 10 Mb/s switch port.
B. This is a 100 Mb/s switch port.
C. This is an Ethernet port operating at half duplex.
D. This is an Ethernet port operating at full duplex.
E. This is a port on a network interface card in a PC.
Explanation/Reference:
Modern Ethernet networks built with switches and full-duplex connections no longer utilize CSMA/CD. CSMA/CD is only used in obsolete shared media Ethernet (which uses repeater or hub).
9. A receiving host computes the checksum on a frame and determines that the frame is damaged. The frame is then discarded. At which OSI layer did this happen?
A. session
B. transport
C. network
D. data link
E. physical
Explanation/Reference:
The Data Link layer provides the physical transmission of the data and handles error notification, network topology, and flow control. The Data Link layer formats the message into pieces, each called a data frame,and adds a customized header containing the hardware destination and source address. Protocols Data Unit (PDU) on Datalink layer is called frame. According to this question the frame is damaged and discarded which will happen at the Data Link layer.
10. Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two.)
A. The transport layer divides a data stream into segments and may add reliability and flow control information
B. The data link layer adds physical source and destination addresses and an FCS to the segment.
C. Packets are created when the network layer encapsulates a frame with source and destination host
addresses and protocol-related control information.
D. Packets are created when the network layer adds Layer 3 addresses and control information to a segment.
E. The presentation layer translates bits into voltages for transmission across the physical link.
Explanation/Reference:
The Application Layer (Layer 7) refers to communications services to applications and is the interface between the network and the application. Examples include. Telnet, HTTP, FTP, Internet browsers, NFS, SMTP gateways, SNMP, X.400 mail, and FTAM. The Presentation Layer (Layer 6) defining data formats, such as ASCII text, EBCDIC text, binary, BCD, and JPEG. Encryption also is defined as a presentation layer service. Examples include. JPEG, ASCII, EBCDIC, TIFF, GIF, PICT, encryption, MPEG, and MIDI.
The Session Layer (Layer 5) defines how to start, control, and end communication sessions. This includes the control and management of multiple bidirectional messages so that the application can be notified if only some of a series of messages are completed. This allows the presentation layer to have a seamless view of an incoming stream of data. The presentation layer can be presented with data if all flows occur in some cases. Examples include. RPC, SQL, NFS, NetBios names, AppleTalk ASP, and DECnet SCP The Transport Layer (Layer 4) defines several functions, including the choice of protocols.
The most important Layer 4 functions are error recovery and flow control. The transport layer may provide for retransmission, i.e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, or it might not, depending on the choice of protocols.
Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included. Examples include. TCP, UDP, and SPX. The Network Layer (Layer 3) defines end-to-end delivery of packets and defines logical addressing to accomplish this. It also defines how routing works and how routes are learned; and how to fragment a packet into smaller packets to accommodate media with smaller maximum transmission unit sizes.
Examples include. IP, IPX, AppleTalk DDP, and ICMP. Both IP and IPX define logical addressing, routing, the learning of routing information, and end-to-end delivery rules. The IP and IPX protocols most closely match the OSI network layer (Layer 3) and are called Layer 3 protocols because their functions most closely match OSI’s Layer 3. The Data Link Layer (Layer 2) is concerned with getting data across one particular link or medium.
The data link protocols define delivery across an individual link. These protocols are necessarily concerned with the type of media in use. Examples includE. IEEE 802.3/802.2, HDLC, Frame Relay, PPP, FDDI, ATM, and IEEE 802.5/802.2.
11. Refer to the graphic. Host A is communicating with the server. What will be the source MAC address of the
frames received by Host A from the server?
A. the MAC address of router interface e0
B. the MAC address of router interface e1
C. the MAC address of the server network interface
D. the MAC address of host A
Explanation/Reference:
Whereas switches can only examine and forward packets based on the contents of the MAC header, routers can look further into the packet to discover the network for which a packet is destined. Routers make forwarding decisions based on the packet’s network-layer header (such as an IPX header or IP header). These network-layer headers contain source and destination network addresses. Local devices address packets to the router’s MAC address in the MAC header. After receiving the packets, the router must perform the following steps:
Check the incoming packet for corruption, and remove the MAC header . The router checks the packet for MAC-layer errors. The router then strips off the MAC header and examines the network- layer header to determine what to do with the packet.
Examine the age of the packet. The router must ensure that the packet has not come too far to be forwarded. For example, IPX headers contain a hop count. By default, 15 hops is the maximum number of hops (or routers) that a packet can cross. If a packet has a hop count of 15, the router discards the packet.
IP headers contain a Time to Live (TTL) value. Unlike the IPX hop count, which increments as the packet is forwarded through each router, the IP TTL value decrements as the IP packet is forwarded through each router. If an IP packet has a TTL value of 1, the router discards the packet. A router cannot decrement the TTL value to 1 and then forward the packet. Determine the route to the destination. Routers maintain a routing table that lists available networks, the direction to the desired network (the outgoing interface number), and the distance to those networks. After determining which direction to forward the packet, the router must build a new header. (If you want to read the IP routing tables on a Windows 95/98 workstation, type
ROUTE PRINT in the DOS box.)
Build the new MAC header and forward the packet. Finally, the router builds a new MAC header for the packet. The MAC header includes the router’s MAC address and the final destination’s MAC address or the MAC address of the next router in the path.
12. Refer to the exhibit. What two results would occur if the hub were to be replaced with a switch that is configured with one Ethernet VLAN? (Choose two.)
A. The number of collision domains would remain the same.
B. The number of collision domains would decrease.
C. The number of collision domains would increase.
D. The number of broadcast domains would remain the same.
E. The number of broadcast domains would decrease.
F. The number of broadcast domains would increase.
Explanation/Reference:
Basically, a collision domain is a network segment that allows normal network traffic to flow back and forth. In the old days of hubs, this meant you had a lot of collisions, and the old CSMA/CD would be working overtime to try to get those packets re-sent every time there was a collision on the wire (since ethernet allows only one host to be transmitting at once without there being a traffic jam). With switches, you break up collision domains by switching packets bound for other collision domains. These days, since we mostly use switches to connect computers to the network, you generally have one collision domain to a PC.
Broadcast domains are exactly what they imply: they are network segments that allow broadcasts to be sent across them. Since switches and bridges allow for broadcast traffic to go unswitched, broadcasts can traverse collision domains freely. Routers, however, don’t allow broadcasts through by default, so when a broadcast hits a router (or the perimeter of a VLAN), it doesn’t get forwarded. The simple way to look at it is this way: switches break up collision domains, while routers (and VLANs) break up collision domains and broadcast domains. Also, a broadcast domain can contain multiple collision domains, but a collision domain can never have more than one broadcast domain associated with it.
Collision Domain: A group of Ethernet or Fast Ethernet devices in a CSMA/CD LAN that are connected by repeaters and compete for access on the network. Only one device in the collision domain may transmit at any one time, and the other devices in the domain listen to the network in order to avoid data collisions. A collision domain is sometimes referred to as an Ethernet segment.
Broadcast Domain: Broadcasting sends a message to everyone on the local network (subnet). An example for Broadcasting would be DHCP Request from a Client PC. The Client is asking for a IP Address, but the client does not know how to reach the DHCP Server. So the client sends a DHCP Discover packet to EVERY PC in the local subnet (Broadcast). But only the DHCP Server will answer to the Request.
How to count them?
Broadcast Domain:
No matter how many hosts or devices are connected together, if they are connected with a repeater, hub, switch or bridge, all these devices are in ONE Broadcast domain (assuming a single VLAN). A Router is used to separate Broadcast-Domains (we could also call them Subnets – or call them VLANs). So, if a router stands between all these devices, we have TWO broadcast domains.
Collision Domain:
Each connection from a single PC to a Layer 2 switch is ONE Collision domain. For example, if 5 PCs are connected with separate cables to a switch, we have 5 Collision domains. If this switch is connected to another switch or a router, we have one collision domain more. If 5 Devices are connected to a Hub, this is ONE Collision Domain. Each device that is connected to a Layer 1 device (repeater, hub) will reside in ONE single collision domain.
13. Which three statements accurately describe Layer 2 Ethernet switches? (Choose three.)
A. Spanning Tree Protocol allows switches to automatically share VLAN information.
B. Establishing VLANs increases the number of broadcast domains.
C. Switches that are configured with VLANs make forwarding decisions based on both Layer 2 and Layer 3 address information.
D. Microsegmentation decreases the number of collisions on the network.
E. In a properly functioning network with redundant switched paths, each switched segment will contain one root bridge with all its ports in the forwarding state. All other switches in that broadcast domain will have only one root port.
F. If a switch receives a frame for an unknown destination, it uses ARP to resolve the address.
Explanation/Reference:
Microsegmentation is a network design (functionality) where each workstation or device on a network gets its own dedicated segment (collision domain) to the switch. Each network device gets the full bandwidth of the segment and does not have to share the segment with other devices. Microsegmentation reduces and can even eliminate collisions because each segment is its own collision domain -> .
Note: Microsegmentation decreases the number of collisions but it increases the number of collision
domains.
14. Where does routing occur within the DoD TCP/IP reference model?
A. application
B. internet
C. network
D. transport
Explanation/Reference:
The picture below shows the comparison between TCP/IP model & OSI model. Notice that the Internet Layer of TCP/IP is equivalent to the Network Layer which is responsible for routing decision.
15. Refer to exhibit: Which destination addresses will be used by Host A to send data to Host C? (Choose two.)
A. the IP address of Switch 1
B. the MAC address of Switch 1
C. the IP address of Host C
D. the MAC address of Host C
E. the IP address of the router’s E0 interface
F. the MAC address of the router’s E0 interface
Explanation/Reference:
While transferring data through many different networks, the source and destination IP addresses are not changed. Only the source and destination MAC addresses are changed. So in this case Host A will use the IP address of Host C and the MAC address of E0 interface to send data.
When the router receives this data, it replaces the source MAC address with it own E1 interface’s MAC address and replaces the destination MAC address with Host C’s MAC address before sending to Host C .
16. For what two purposes does the Ethernet protocol use physical addresses? (Choose two.)
A. to uniquely identify devices at Layer 2
B. to allow communication with devices on a different network
C. to differentiate a Layer 2 frame from a Layer 3 packet
D. to establish a priority system to determine which device gets to transmit first
E. to allow communication between different devices on the same network
F. to allow detection of a remote device when its physical address is unknown
Explanation/Reference:
Physical addresses or MAC addresses are used to identify devices at layer 2. MAC addresses are only used to communicate on the same network. To communicate on different networkwe have to use Layer 3 addresses (IP addresses) -> B is not correct. Layer 2 frame and Layer 3 packet can be recognized via headers. Layer 3 packet also contains physical address ->
On Ethernet, each frame has the same priority to transmit by default -> All devices need a physical address to identify itself. If not, they can not communicate ->
17. Refer to the exhibit. Based on the information given, which switch will be elected root bridge and why?
A. Switch A, because it has the lowest MAC address
B. Switch A, because it is the most centrally located switch
C. Switch B, because it has the highest MAC address
D. Switch C, because it is the most centrally located switch
E. Switch C, because it has the lowest priority
F. Switch D, because it has the highest priority
Explanation/Reference:
To elect the root bridge in the LAN, first check the priority value. The switch having the lowest priority will win the election process. If Priority Value is the same then it checks the MAC Address; the switch having the lowest MAC Address will become the root bridge. In this case, switch C has the lowest MAC Address so it becomes the root bridge.
18. Refer to the exhibit. Switch-1 needs to send data to a host with a MAC address of 00b0.d056.efa4. What will Switch-1 do with this data?
A. Switch-1 will drop the data because it does not have an entry for that MAC address.
B. Switch-1 will flood the data out all of its ports except the port from which the data originated. C. Switch-1 will send an ARP request out all its ports except the port from which the data originated.
D. Switch-1 will forward the data to its default gateway.
Explanation/Reference:
This question tests the operating principles of the Layer 2 switch. Check the MAC address table of Switch1 and find that the MAC address of the host does not exist in the table. Switch1 will flood the data out all of its ports except the port from which the data originated to determine which port the host is located in. Switches work as follows: In output there is no MAC address of give host so switch floods to all ports except the source port.
19. What value is primarily used to determine which port becomes the root port on each nonroot switch in a spanning-tree topology?
A. path cost
B. lowest port MAC address
C. VTP revision number
D. highest port priority number
E. port priority number and MAC address
Explanation/Reference:
The path cost to the root bridge is the most important value to determine which port will become the root port on each non-root switch. In particular, the port with lowest cost to the root bridge will become root port (on non-root switch).
20. What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?
A. It creates a VLAN 999 interface
B. It designates VLAN 999 for untagged traffic.
C. It blocks VLAN 999 traffic from passing on the trunk.
D. It designates VLAN 999 as the default for all unknown tagged traffic.
Explanation/Reference:
Configuring the Native VLAN for Untagged Traffic A trunk port configured with 802.1Q tagging can receive both tagged and untagged traffic. By default, the switch forwards untagged traffic in the native VLAN configured for the port. The native VLAN is VLAN 1 by default.
21. Which two protocols are used by bridges and/or switches to prevent loops in a layer 2 network? (Choose two.)
A. 802.1d
B. VTP
C. 802.1q
D. STP
E. SAP
Explanation/Reference:
This question is to examine the STP protocol.
STP (802.1d) is used to prevent Layer 2 loops.
802.1q is a Frame Relay protocol which belongs to VLAN.
SAP is a concept of the OSI model.
22. Which switch would STP choose to become the root bridge in the selection process?
A. 32768: 11-22-33-44-55-66
B. 32768: 22-33-44-55-66-77
C. 32769: 11-22-33-44-55-65
D. . 32769: 22-33-44-55-66-78
23. A switch is configured with all ports assigned to vlan 2 with full duplex FastEthernet to segment existing departmental traffic. What is the effect of adding switch ports to a new VLAN on the switch?
A. More collision domains will be created.
B. IP address utilization will be more efficient.
C. More bandwidth will be required than was needed previously.
D. An additional broadcast domain will be created.
Explanation/Reference:
Each VLAN creates its own broadcast domain. Since this is a full duplex switch, each port is a separate collision domain.
24. What are three benefits of implementing VLANs? (Choose three.)
A. A higher level of network security can be reached by separating sensitive data traffic from other network traffic.
B. A more efficient use of bandwidth can be achieved allowing many physical groups to use the same
network infrastructure.
C. A more efficient use of bandwidth can be achieved allowing many logical networks to use the same network infrastructure.
D. Broadcast storms can be mitigated by increasing the number of broadcast domains, thus reducing their size.
E. Broadcast storms can be mitigated by decreasing the number of broadcast domains, thus increasing
their size.
F. VLANs make it easier for IT staff to configure new logical groups, because the VLANs all belong to the same broadcast domain.
G. Port-based VLANs increase switch-port use efficiency, thanks to 802.1Q trunks.
Explanation/Reference:
Benefits of VLANs
VLAN is a network structure which allows users to communicate while in different locations by sharing one multicast domain and a single broadcast. They provide numerous networking benefits and have become popular in the market. For instance, it helps reduce administrative costs when users are geographically
dispersed.
1. Inexpensive
The popularity of VLANs is due to the fact that changes, adds, and moves can be attained simply by making necessary configurations on the VLAN port. Time-consuming, re-addressing, and host reconfigurations is now a thing of the past, because network configuration can be made at ease when need arises.
2. Better management
A VLAN typically solve the scalability issues that exist in a large network by breaking the main domain into several VLAN groups or smaller broadcast configurations, thereby encourage better control of multicast traffic as well as broadcast domains. Improves network security High-security can be positioned in different VLAN groups to ensure that non-members cannot receive their broadcasts. On the other hand, a router is added and workgroups relocated into centralized locations.
Enhances performance A more efficient use of bandwidth can be achieved allowing many logical networks to use the same network infrastructure.
5. Segment multiple networks
VLANs are typically used to achieve multiple purposes. They are popularly used to reduce broadcast traffic. Each VLAN creates a separate, smaller broadcast domain.
6. Better administration
VLANs facilitate grouping of multiple geographical stations. When VLAN users move to another physical
location, the network does not have to be configured.
25. Which IEEE standard protocol is initiated as a result of successful DTP completion in a switch over Fast Ethernet?
A. 802.3ad
B. 802.1w
C. 802.1D
D. 802.1Q
Explanation/Reference:
Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol for negotiating trunking on a link between two devices and for negotiating the type of trunking encapsulation (802.1Q) to be used.
26. Which of the following are benefits of VLANs? (Choose three.)
A. They increase the size of collision domains.
B. They allow logical grouping of users by function.
C. They can enhance network security.
D. They increase the size of broadcast domains while decreasing the number of collision domains.
E. They increase the number of broadcast domains while decreasing the size of the broadcast domains.
F. They simplify switch administration.
Explanation/Reference:
When using VLAN the number and size of collision domains remain the same -> VLANs allow to group users by function, not by location or geography -> . VLANs help minimize the incorrect configuration of VLANs so it enhances the security of the network -> . VLAN increases the size of broadcast domains but does not decrease the number of collision domains ->
VLANs increase the number of broadcast domains while decreasing the size of the broadcast domains which increase the utilization of the links. It is also a big advantage of VLAN -> . VLANs are useful but they are more complex and need more administration ->
27. Refer to the exhibit. A technician has installed SwitchB and needs to configure it for remote access from the management workstation connected to SwitchA . Which set of commands is required to accomplish this task?
A. SwitchB(config)# interface FastEthernet 0/1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# no shutdown
B. B. SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# ip default-gateway 192.168.8.254 255.255.255.0 SwitchB
(config-if)# no shutdown
C. SwitchB(config)# ip default-gateway 192.168.8.254
SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0 SwitchB(config-
if)# no shutdown
D. SwitchB(config)# ip default-network 192.168.8.254
SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0 SwitchB(config-
if)# no shutdown
E. SwitchB(config)# ip route 192.168.8.254 255.255.255.0
SwitchB(config)# interface FastEthernet 0/1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# no shutdown
Explanation/Reference:
To remote access to SwitchB, it must have a management IP address on a VLAN on that switch. Traditionally, we often use VLAN 1 as the management VLAN (but in fact it is not secure). In the exhibit, we can recognize that the Management Workstation is in a different subnet from the SwitchB. For intersubnetwork communication to occur, you must configure at least one default gateway. This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.
28. In an Ethernet network, under what two scenarios can devices transmit? (Choose two.)
A. when they receive a special token
B. when there is a carrier
C. when they detect no other devices are sending
D. when the medium is idle
E. when the server grants access
Explanation/Reference:
Ethernet network is a shared environment so all devices have the right to access to the medium. If more than one device transmits simultaneously, the signals collide and can not reach the destination. If a device detects another device is sending, it will wait for a specified amount of time before attempting to transmit.
When there is no traffic detected, a device will transmit its message. While this transmission is occurring, the device continues to listen for traffic or collisions on the LAN. After the message is sent, the device returns to its default listening mode.
29. Which two states are the port states when RSTP has converged? (Choose two.)
A. discarding
B. listening
C. learning
D. forwarding
E. disabled
30. Which two commands can be used to verify a trunk link configuration status on a given Cisco switch interface? (Choose two.)
A. show interface trunk
B. show interface interface
C. show ip interface brief
D. show interface vlan
E. show interface switchport
31. Which of the following statements describe the network shown in the graphic? (Choose two.)
A. There are two broadcast domains in the network.
B. There are four broadcast domains in the network.
C. There are six broadcast domains in the network
D. There are four collision domains in the network.
E. There are five collision domains in the network.
F. There are seven collision domains in the network.
Explanation/Reference:
Explanation:
Only router can break up broadcast domains so in the exhibit there are 2 broadcast domains: from e0 interface to the left is a broadcast domain and from e1 interface to the right is another broadcast domain ->.
Both router and switch can break up collision domains so there is only 1 collision domain on the left of the router (because hub doesn’t break up collision domain) and there are 6 collision domains on the right of the router (1 collision domain from e1 interface to the switch + 5 collision domains for 5 PCs in Production) ->
32. Which command enables RSTP on a switch?
A. spanning-tree uplinkfast
B. spanning-tree mode rapid-pvst
C. spanning-tree backbonefast
D. spanning-tree mode mst
Explanation/Reference:
Ethernet network is a shared environment so all devices have the right to access to the medium. If more than one device transmits simultaneously, the signals collide and can not reach the destination. If a device detects another device is sending, it will wait for a specified amount of time before attempting to transmit.
When there is no traffic detected, a device will transmit its message. While this transmission is occurring, the device continues to listen for traffic or collisions on the LAN. After the message is sent, the device returns to its default listening mode.
33. Refer to the exhibit. All switch ports are assigned to the correct VLANs, but none of the hosts connected to SwitchA can communicate with hosts in the same VLAN connected to SwitchB. Based on the output shown, what is the most likely problem?
A. The access link needs to be configured in multiple VLANs.
B. The link between the switches is configured in the wrong VLAN.
C. The link between the switches needs to be configured as a trunk.
D. VTP is not configured to carry VLAN information between the switches.
E. Switch IP addresses must be configured in order for traffic to be forwarded between the switches.
Explanation/Reference:
In order to pass traffic from VLANs on different switches, the connections between the switches must be configured as trunk ports.
34. What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?
A. It creates a VLAN 999 interface.
B. It designates VLAN 999 for untagged traffic.
C. It blocks VLAN 999 traffic from passing on the trunk.
D. It designates VLAN 999 as the default for all unknown tagged traffic.
Explanation/Reference:
Configuring the Native VLAN for Untagged Traffic A trunk port configured with 802.1Q tagging can receive both tagged and untagged traffic. By default, the switch forwards untagged traffic in the native VLAN configured for the port. The native VLAN is VLAN 1 by default.
35. Refer to the exhibit. Given the output shown from this Cisco Catalyst 2950, what is the reason that interface FastEthernet 0/10 is not the root port for VLAN 2?
A. This switch has more than one interface connected to the root network segment in VLAN 2.
B. This switch is running RSTP while the elected designated switch is running 802.1d Spanning Tree.
C. This switch interface has a higher path cost to the root bridge than another in the topology.
D. This switch has a lower bridge ID for VLAN 2 than the elected designated switch.
Explanation/Reference:
Since the port is in the blocked status, we must assume that there is a shorter path to the root bridge
elsewhere.
36. Why will a switch never learn a broadcast address?
A. Broadcasts only use network layer addressing.
B. A broadcast frame is never forwarded by a switch.
C. A broadcast address will never be the source address of a frame.
D. Broadcast addresses use an incorrect format for the switching table.
E. Broadcast frames are never sent to switches.
Explanation/Reference:
Switches dynamically learn MAC addresses based on the source MAC addresses that it sees, and since a broadcast is never the source, it will never learn the broadcast address.
37. Refer to the exhibit. Why has this switch not been elected the root bridge for VLAN1?
A. It has more than one interface that is connected to the root network segment.
B. It is running RSTP while the elected root bridge is running 802.1d spanning tree
C. It has a higher MAC address than the elected root bridge.
D. It has a higher bridge ID than the elected root bridge.
Explanation/Reference:
The root bridge is determined by the lowest bridge ID, and this switch has a bridge ID priority of 32768, which is higher than the roots priority of 20481.
38. Which two link protocols are used to carry multiple VLANs over a single link? (Choose two.)
A. VTP
B. 802.1q
C. IGP
D. ISL
E. 802.3u
Explanation/Reference:
Cisco switches can use two different encapsulation types for trunks, the industry standard 802.1q or the Cisco proprietary ISL. Generally, most network engineers prefer to use 802.1q since it is standards based and will interoperate with other vendors.
39. Assuming the default switch configuration, which VLAN range can be added, modified, and removed on a Cisco switch?
A. 1 through 1001
B. 2 through 1001
C. 1 through 1002
D. 2 through 1005
Explanation/Reference:
VLAN 1 is the default VLAN on Cisco switch. It always exists and can not be added, modified or removed.
VLANs 1002-1005 are default VLANs for FDDI & Token Ring and they can’t be deleted or used for
Ethernet.
40. Which statement about VLAN operation on Cisco Catalyst switches is true?
A. When a packet is received from an 802.1Q trunk, the VLAN ID can be determined from the source
MAC address and the MAC address table.
B. Unknown unicast frames are retransmitted only to the ports that belong to the same VLAN.
C. Broadcast and multicast frames are retransmitted to ports that are configured on different VLAN.
D. Ports between switches should be configured in access mode so that VLANs can span across the
ports.
41. Refer to the topology shown in the exhibit. Which ports will be STP designated ports if all the links ar operating at the same bandwidth? (Choose three.)
A. Switch A – Fa0/0
B. Switch A – Fa0/1
C. Switch B – Fa0/0
D. Switch B – Fa0/1
E. Switch C – Fa0/0
F. Switch C – Fa0/1
Explanation/Reference:
This question is to check the spanning tree election problem. First, select the root bridge, which can be accomplished by comparing the bridge ID, the smallest will be selected. Bridge-id= bridge priority + MAC address. The three switches in the figure all have the default priority, so we should compare the MAC address, it is easy to find that SwitchB is the root bridge.
Select the root port on the non-root bridge, which can be completed through comparing root path cost. The smallest will be selected as the root port.
Next, select the Designated Port. First, compare the path cost, if the costs happen to be the same, then compare the BID, still the smallest will be selected. Each link has a DP. Based on the exhibit above, we can find DP on each link. The DP on the link between SwitchA and SwitchC is SwitchA’Fa0/1, because it has the smallest MAC address.
42. Refer to the exhibit. How should the FastEthernet0/1 ports on the 2950 model switches that are shown in the exhibit be configured to allow connectivity between all devices?
A. The ports only need to be connected by a crossover cable.
B. SwitchX(config)# interface fastethernet 0/1
SwitchX(config-if)# switchport mode trunk
C.SwitchX (config)# interface fastethernet 0/1
SwitchX (config-if)# switchport mode trunk
D.SwitchX(config)# interface fastethernet 0/1
SwitchX(config-if)# switchport mode trunk
43. Which three statements about RSTP are true? (Choose three.)
A. RSTP significantly reduces topology reconverging time after a link failure.
B. RSTP expands the STP port roles by adding the alternate and backup roles
C. RSTP port states are blocking, discarding, learning, or forwarding.
D. RSTP provides a faster transition to the forwarding state on point-to-point links than STP does.
E. RSTP also uses the STP proposal-agreement sequence.
F. RSTP uses the same timer-based process as STP on point-to-point links.
Explanation/Reference:
One big disadvantage of STP is the low convergence which is very important in switched network. To overcome this problem, in 2001, the IEEE with document 802.1w introduced an evolution of the Spanning Tree Protocol: Rapid Spanning Tree Protocol (RSTP), which significantly reduces the convergence time after a topology change occurs in the network. While STP can take 30 to 50 seconds to transit from a blocking state to a forwarding state, RSTP is typically able to respond less than 10 seconds of a physical link failure.
RSTP works by adding an alternative port and a backup port compared to STP. These ports are allowed to immediately enter the forwarding state rather than passively wait for the network to converge. RSTP bridge port roles: Root port – A forwarding port that is the closest to the root bridge in terms of path cost Designated port – A forwarding port for every LAN segment
Alternate port – A best alternate path to the root bridge. This path is different than using the root port. The alternative port moves to the forwarding state if there is a failure on the designated port for the segment.
Backup port – A backup/redundant path to a segment where another bridge port already connects. The backup port applies only when a single switch has two links to the same segment (collision domain). To have two links to the same collision domain, the switch must be attached to a hub. Disabled port – Not strictly part of STP, a network administrator can manually disable a port
44. Refer to the exhibit. A frame on VLAN 1 on switch S1 is sent to switch S2 where the frame is received on VLAN 2. What causes this behavior?
A. trunk mode mismatches
B. allowing only VLAN 2 on the destination
C. native VLAN mismatches
D. VLANs that do not correspond to a unique IP subnet
Explanation/Reference:
Untagged frames are encapsulated with the native VLAN. In this case, the native VLANs are different so although S1 will tag it as VLAN 1 it will be received by S2.
45. At which layer of the OSI model is RSTP used to prevent loops?
A. physical
B. data link
C. network
D. transport
Explanation/Reference:
RSTP and STP operate on switches and are based on the exchange of Bridge Protocol Data Units (BPDUs) between switches. One of the most important fields in BPDUs is the Bridge Priority in which the MAC address is used to elect the Root Bridge -> RSTP operates at Layer 2 ?Data Link layer -> .
46. What does a Layer 2 switch use to decide where to forward a received frame?
A. source MAC address
B. source IP address C. source switch port
C. destination IP address
D. destination port address
E. source switch port
F. destination MAC address
Explanation/Reference:
When a frame is received, the switch looks at the destination hardware address and finds the interface if it is in its MAC address table. If the address is unknown, the frame is broadcast on all interfaces except the one it was received on.
47. Refer to the exhibit. Which statement is true?
A. The Fa0/11 role confirms that SwitchA is the root bridge for VLAN 20.
B. VLAN 20 is running the Per VLAN Spanning Tree Protocol.
C. The MAC address of the root bridge is 0017.596d.1580.
D. SwitchA is not the root bridge, because not all of the interface roles are designated.
Explanation/Reference:
Only non-root bridge can have root port. Fa0/11 is the root port so we can confirm this switch is not the root bridge ->
From the output we learn this switch is running Rapid STP, not PVST -> 0017.596d.1580 is the MAC address of this switch, not of the root bridge. The MAC address of the root bridge is 0017.596d.2a00 -> All of the interface roles of the root bridge are designated. SwitchA has one Root port and 1 Alternative port so it is not the root bridge.
48. Which two benefits are provided by creating VLANs? (Choose two.)
A. added security
B. dedicated bandwidth
C. provides segmentation
D. allows switches to route traffic between subinterfaces
E. contains collisions
Explanation/Reference:
A VLAN is a switched network that is logically segmented on an organizational basis, by functions, project teams, or applications rather than on a physical or geographical basis. Security: VLANs also improve security by isolating groups. High-security users can be grouped into a VLAN, possible on the same physical segment, and no users outside that VLAN can communicate with them LAN Segmentation VLANs allow logical network topologies to overlay the physical switched infrastructure such that any arbitrary collection of LAN ports can be combined into an autonomous user group or community of interest. The technology logically segments the network into separate Layer 2 broadcast domains whereby packets
are switched between ports designated to be within the same VLAN. By containing traffic originating on a particular LAN only to other LANs in the same VLAN, switched virtual networks avoid wasting bandwidth.
49. Which command can be used from a PC to verify the connectivity between hosts that connect through a switch in the same LAN?
A. pingaddress
B. tracert address
C. traceroute address
D. arpaddress
Explanation/Reference:
ICMP pings are used to verify connectivity between two IP hosts. Traceroute is used to verify the router hop path traffic will take but in this case since the hosts are in the same LAN there will be no router hops involved.
50. Based on the network shown in the graphic. Which option contains both the potential networking problem and the protocol or setting that should be used to prevent the problem?
A. routing loops, hold down timers
B. switching loops, split horizon
C. routing loops, split horizon
D. switching loops, VTP
E. routing loops, STP
F. switching loops, STP
Explanation/Reference:
The Spanning-Tree Protocol (STP) prevents loops from being formed when switches or bridges are interconnected via multiple paths. Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices.
51. Refer to the exhibit. Which two statements are true about interVLAN routing in the topology that is shown in the exhibit? (Choose two.)
A. Host E and host F use the same IP gateway address.
B. Router1 and Switch2 should be connected via a crossover cable.
C. Router1 will not play a role in communications between host A and host D
D. The FastEthernet 0/0 interface on Router1 must be configured with subinterfaces.
E. Router1 needs more LAN interfaces to accommodate the VLANs that are shown in the exhibit.
F. The FastEthernet 0/0 interface on Router1 and the FastEthernet 0/1 interface on Switch2 trunk ports must be configured using the same encapsulation type
52. Which two of these are characteristics of the 802.1Q protocol? (Choose two.)
A. It is used exclusively for tagging VLAN frames and does not address network reconvergence
B. It modifies the 802.3 frame header, and thus requires that the FCS be recomputed.
C. It is a Layer 2 messaging protocol which maintains VLAN configurations across networks.
D. It includes an 8-bit field which specifies the priority of a frame.
E. It is a trunking protocol capable of carrying untagged frames.
Explanation/Reference:
802.1Q protocol, or Virtual Bridged Local Area Networks protocol, mainly stipulates the realization of the VLAN. 802.1Q is a standardized relay method that inserts 4 bytes field into the original Ethernet frame and re-calculate the FCS. 802.1Q frame relay supports two types of frame: marked and non-marked. Non- marked frame carries no VLAN identification information.
53. Refer to the exhibit. Each of these four switches has been configured with a hostname, as well as being configured to run RSTP. No other configuration changes have been made. Which three of these show the correct RSTP port roles for the indicated switches and interfaces? (Choose three.)
A. SwitchA, Fa0/2, designated
B. SwitchA, Fa0/1, root
C. SwitchB, Gi0/2, root
D. SwitchB, Gi0/1, designated
E. SwitchC, Fa0/2, root
F. SwitchD, Gi0/2, root
Explanation/Reference:
The question says “no other configuration changes have been made” so we can understand these switches have the same bridge priority. Switch C has lowest MAC address so it will become root bridge and 2 of its ports (Fa0/1 & Fa0/2) will be designated ports. Because SwitchC is the root bridge so the 2 ports nearest SwitchC on SwitchA (Fa0/1) and SwitchD (Gi0/2) will be root ports..
Now we come to the most difficult part of this question: SwitchB must have a root port so which port will it choose? To answer this question we need to know about STP cost and port cost. In general, “cost” is calculated based on bandwidth of the link. The higher the bandwidth on a link, the lower the value of its cost. Below are the cost values you should memorize:
SwitchB will choose the interface with lower cost to the root bridge as the root port so we must calculate the cost on interface Gi0/1 & Gi0/2 of SwitchB to the root bridge. This can be calculated from the “cost to the root bridge” of each switch because a switch always advertises its cost to the root bridge in its BPDU. The receiving switch will add its local port cost value to the cost in the BPDU. One more thing to notice is that a root bridge always advertises the cost to the root bridge (itself) with an initial value of 0. Now let’s have a look at the topology again
SwitchC advertises its cost to the root bridge with a value of 0. Switch D adds 4 (the cost value of 1Gbps link) and advertises this value (4) to SwitchB. SwitchB adds another 4 and learns that it can reach SwitchC via Gi0/1 port with a total cost of 8. The same process happens for SwitchA and SwitchB learns that it canreach SwitchC via Gi0/2 with a total cost of 23 -> Switch B chooses Gi0/1 as its root port ->
Now our last task is to identify the port roles of the ports between SwitchA & SwitchB. It is rather easy as the MAC address of SwitchA is lower than that of SwitchB so Fa0/2 of SwitchA will be designated port while Gi0/2 of SwitchB will be alternative port.
Below summaries all the port roles of these switches:
+ DP: Designated Port (forwarding state)
+ RP: Root Port (forwarding state)
54. What is one benefit of PVST+?
A. PVST+ supports Layer 3 load balancing without loops.
B. PVST+ reduces the CPU cycles for all the switches in the network.
C. PVST+ allows the root switch location to be optimized per VLAN.
D. PVST+ automatically selects the root bridge location, to provide optimized bandwidth usage.
Explanation/Reference:
The PVST+ provides Layer 2 load-balancing for the VLAN on which it runs. You can create different logical topologies by using the VLANs on your network to ensure that all of your links are used but that no one link is oversubscribed. Each instance of PVST+ on a VLAN has a single root switch. This root switch propagates the spanning-tree information associated with that VLAN to all other switches in the network.
Because each switch has the same information about the network, this process ensures that the network topology is maintained and optimized per VLAN. http://www.cisco.com/en/US/docs/switches/lan/ catalyst3750x_3560x/software/release/12.2_55_s e/configuration/guide/swstp.html
55. Refer to the exhibit. The network administrator normally establishes a Telnet session with the switch from host A . However, host A is unavailable. The administrator’s attempt to telnet to the switch from host B fails, but pings to the other two hosts are successful. What is the issue?
A. Host B and the switch need to be in the same subnet.
B. The switch interface connected to the router is down.
C. Host B needs to be assigned an IP address in VLAN 1.
D. The switch needs an appropriate default gateway assigned.
E. The switch interfaces need the appropriate IP addresses assigned.
Explanation/Reference:
Ping was successful form host B to other hosts because of intervlan routing configured on router. But to manage switch via telnet the VLAN32 on the switch needs to be configured interface vlan32 along with ip address and its appropriate default-gateway address. Since VLAN1 interface is already configure on switch Host A was able to telnet switch.
56. Which are valid modes for a switch port used as a VLAN trunk? (Choose three.)
A. transparent
B. auto
C. on
D. desirable
E. blocking
F. forwarding
57.Refer to the exhibit. Which switch provides the spanning-tree designated port role for the network segment that services the printers?
A. SW1
B. SW2
C. SW3
D. SW4
Explanation/Reference:
Printers are connected by hubs. Decide the switch that provides the spanning-tree designated port role between Switch3 and Switch4. They have the same priority 32768. Compare their MAC addresses. Switch3 with a smaller MAC address will provide a designated port for printers.
58. Refer to Exhibit. How many broadcast domains are shown in the graphic assuming only the default VLAN is
configured on the switches?
A. 1
B. 2
C. 6
D. 11
Explanation/Reference:
Only router can break up broadcast domains but in this exhibit no router is used so there is only 1 broadcast domain.
For your information, there are 7 collision domains in this exhibit (6 collision domains between hubs & switches + 1 collision between the two switches).
59. Which three of these statements regarding 802.1Q trunking are correct? (Choose three.)
A. 802.1Q native VLAN frames are untagged by default.
B. 802.1Q trunking ports can also be secure ports.
C. 802.1Q trunks can use 10 Mb/s Ethernet interfaces.
D. 802.1Q trunks require full-duplex, point-to-point connectivity.
E. 802.1Q trunks should have native VLANs that are the same at both ends.
Explanation/Reference:
By default, 802.1Q trunk defined Native VLAN in order to forward unmarked frame. Switches can forward Layer 2 frame from Native VLAN on unmarked trunks port. Receiver switches will transmit all unmarked packets to Native VLAN. Native VLAN is the default VLAN configuration of port. Note for the 802.1Q trunk ports between two devices, the same Native VLAN configuration is required on both sides of the link. If the Native VLAN in 802.1Q trunk ports on same trunk link is properly configured, it could lead to layer 2 loops. The 802.1Q trunk link transmits VLAN information through Ethernet.
60. Refer to the exhibit. The output that is shown is generated at a switch. Which three statements are true? (Choose three.)
A. All ports will be in a state of discarding, learning, or forwarding.
B. Thirty VLANs have been configured on this switch.
C. The bridge priority is lower than the default value for spanning tree.
D. All interfaces that are shown are on shared media.
E. All designated ports are in a forwarding state. F. This switch must be the root bridge for all VLANs on this switch.
Explanation/Reference:
From the output, we see that all ports are in Designated role (forwarding state). The command “show spanning-tree vlan 30 only shows us information about VLAN 30. We don’t know how many VLAN exists in
this switch ->
The bridge priority of this switch is 24606 which is lower than the default value bridge priority 32768 -> . All three interfaces on this switch have the connection type “p2p”, which means Point-to-point environment ?not a shared media >;
The only thing we can specify is this switch is the root bridge for VLAN 3o but we can not guarantee it is also the root bridge for other VLANs ->
61. Refer to the exhibit. At the end of an RSTP election process, which access layer switch port will assume the
discarding role?
A. Switch3, port fa0/1
B. Switch3, port fa0/12
C. Switch4, port fa0/11
D. Switch4, port fa0/2
E. Switch3, port Gi0/1
F. Switch3, port Gi0/2
Explanation/Reference:
In this question, we only care about the Access Layer switches (Switch3 & 4). Switch 3 has a lower bridge ID than Switch 4 (because the MAC of Switch3 is smaller than that of Switch4) so both ports of Switch3 will be in forwarding state. The alternative port will surely belong to Switch4. Switch4 will need to block one of its ports to avoid a bridging loop between the two switches. But how does Switch4 select its blocked port?
Well, the answer is based on the BPDUs it receives from Switch3. A BPDU is superior than another if it has:
A lower Root Bridge ID
A lower path cost to the Root
A lower Sending Bridge ID
A lower Sending Port ID
These four parameters are examined in order. In this specific case, all the BPDUs sent by Switch3 have the same Root Bridge ID, the same path cost to the Root and the same Sending Bridge ID.The only parameter left to select the best one is the Sending Port ID (Port ID = port priority + port index). In this case the port priorities are equal because they use the default value, so Switch4 will compare port index values, which are unique to each port on the switch, and because Fa0/12 is inferior to Fa0/1, Switch4 will select the port connected with Fa0/1 (of Switch3) as its root port and block the other port -> Port fa0/11 of Switch4 will be blocked (discarding role).
62. Which term describes a spanning-tree network that has all switch ports in either the blocking or fowarding
state?
A. converged
B. redundant
C. provisioned
D. spanned
Explanation/Reference:
Spanning Tree Protocol convergence (Layer 2 convergence) happens when bridges and switches have transitioned to either the forwarding or blocking state. When layer 2 is converged, root bridge is elected and all port roles (Root, Designated and Non-Designated) in all switches are selected.
63. What are the possible trunking modes for a switch port? (Choose three.)
A. transparent
B. auto
C. on
D. desirable
E. client
F. forwarding
64. Which two of these statements regarding RSTP are correct? (Choose two.)
A. RSTP cannot operate with PVST+.
B. RSTP defines new port roles.
C. RSTP defines no new port states.
D. RSTP is a proprietary implementation of IEEE 802.1D STP.
E. RSTP is compatible with the original IEEE 802.1D STP.
Explanation/Reference:
When network topology changes, rapid spanning tree protocol (IEEE802.1W, referred to as RSTP) will speed up significantly the speed to re-calculate spanning tree. RSTP not only defines the role of other ports: alternative port and backup port, but also defines status of 3 ports: discarding status, learning status,forwarding status. RSTP is 802.1D standard evolution, not revolution. It retains most of the parameters, and makes no changes.
65. Refer to the exhibit. Which two statements are true of the interfaces on Switch1? (Choose two.)
A. Multiple devices are connected directly to FastEthernet0/1.
B. A hub is connected directly to FastEthernet0/5.
C. FastEthernet0/1 is connected to a host with multiple network interface cards.
D. FastEthernet0/5 has statically assigned MAC addresses.
E. FastEthernet0/1 is configured as a trunk link.
F. Interface FastEthernet0/2 has been disabled.
Explanation/Reference:
Carefully observe the information given after command show. Fa0/1 is connected to Switch2, seven MAC addresses correspond to Fa0/1, and these MAC are in different VLAN. From this we know that Fa0/1 is the trunk interface.
From the information given by show cdp neighbors we find that there is no Fa0/5 in CDP neighbor. However, F0/5 corresponds to two MAC addresses in the same VLAN. Thus we know that Fa0/5 is connected to a Hub. Based on the output shown, there are multiple MAC addresses from different VLANs attached to the FastEthernet 0/1 interface. Only trunks are able to pass information from devices in multiple VLANs.
66. Three switches are connected to one another via trunk ports. Assuming the default switch configuration, which switch is elected as the root bridge for the spanning-tree instance of VLAN 1?
A. the switch with the highest MAC address
B. the switch with the lowest MAC address
C. the switch with the highest IP address
D. the switch with the lowest IP address
Explanation/Reference:
Each switch in your network will have a Bridge ID Priority value, more commonly referred to as a BID. This BID is a combination of a default priority value and the switch’s MAC address, with the priority value listed first. The lowest BID will win the election process.
For example, if a Cisco switch has the default priority value of 32,768 and a MAC address of 11- 22-33-44- 55-66, the BID would be 32768:11-22-33-44-55-66. Therefore, if the switch priority is left at the default, the MAC address is the deciding factor in the root bridge election.
67. What are three advantages of VLANs? (Choose three.)
A. VLANs establish broadcast domains in switched networks.
B. VLANs utilize packet filtering to enhance network security.
C. VLANs provide a method of conserving IP addresses in large networks.
D. VLANs provide a low-latency internetworking alternative to routed networks.
E. VLANs allow access to network services based on department, not physical location.
F. VLANs can greatly simplify adding, moving, or changing hosts on the network.
Explanation/Reference:
VLAN technology is often used in practice, because it can better control layer2 broadcast to improve network security. This makes network more flexible and scalable. Packet filtering is a function of firewall
instead of VLAN.
68. Which two benefits are provided by using a hierarchical addressing network addressing scheme? (Choose two.)
A. reduces routing table entries
B. auto-negotiation of media rates
C. efficient utilization of MAC addresses
D. dedicated communications between devices
E. ease of management and troubleshooting
Explanation/Reference:
Here are some of the benefits of hierarchical addressing: Reference: http://www.ciscopress.com/articles/article.asp p=174107
69. What is the alternative notation for the IPv6 address B514:82C3:0000:0000:0029:EC7A:0000:EC72?
A. B514 : 82C3 : 0029 : EC7A : EC72
B. B514 : 82C3 :: 0029 : EC7A : EC72
C. B514 : 82C3 : 0029 :: EC7A : 0000 : EC72
D. B514 : 82C3 :: 0029 : EC7A : 0 : EC72
Explanation/Reference:
There are two ways that an IPv6 address can be additionally compressed: compressing leading zeros and substituting a group of consecutive zeros with a single double colon (::). Both of these can be used in any number of combinations to notate the same address. It is important to note that the double colon (::) can only be used once within a single IPv6 address notation. So, the extra 0’s can only be compressed once.
70. Refer to the diagram. All hosts have connectivity with one another. Which statements describe the addressing scheme that is in use in the network? (Choose three.)
A. The subnet mask in use is 255.255.255.192.
B. The subnet mask in use is 255.255.255.128.
C. The IP address 172.16.1.25 can be assigned to hosts in VLAN1
D. The IP address 172.16.1.205 can be assigned to hosts in VLAN1
E. The LAN interface of the router is configured with one IP address.
F. The LAN interface of the router is configured with multiple IP addresses.
Explanation/Reference:
The subnet mask in use is 255.255.255.128: This is subnet mask will support up to 126 hosts, which is
needed. The IP address 172.16.1.25 can be assigned to hosts in VLAN1: The usable host range in this subnet is
172.16.1.1-172.16.1.126 The LAN interface of the router is configured with multiple IP addresses: The router will need 2
subinterfaces for the single physical interface, one with an IP address that belongs in each VLAN.
71. Which two statements describe characteristics of IPv6 unicast addressing? (Choose two.)
A. Global addresses start with 2000::/3.
B. Link-local addresses start with FE00:/12.
C. Link-local addresses start with FF00::/10.
D. There is only one loopback address and it is ::1.
E. If a global address is assigned to an interface, then that is the only allowable address for the interface.
Explanation/Reference:
Below is the list of common kinds of IPv6 addresses:
72. The network administrator has been asked to give reasons for moving from IPv4 to IPv6. What are two valid reasons for adopting IPv6 over IPv4? (Choose two.)
A. no broadcast
B. change of source address in the IPv6 header
C. change of destination address in the IPv6 header
D. Telnet access does not require a password
E. autoconfiguration
F. NAT
Explanation/Reference:
IPv6 does not use broadcasts, and autoconfiguration is a feature of IPV6 that allows for hosts to automatically obtain an IPv6 address.
73. An administrator must assign static IP addresses to the servers in a network. For network 192.168.20.24/29, the router is assigned the first usable host address while the sales server is given the last usable host address. Which of the following should be entered into the IP properties box for the sales server?
A. IP address: 192.168.20.14 Subnet Mask: 255.255.255.248
Default Gateway: 192.168.20.9
B. IP address: 192.168.20.254 Subnet Mask: 255.255.255.0 Default Gateway:
192.168.20.1
C. IP address: 192.168.20.30 Subnet Mask: 255.255.255.248
Default Gateway: 192.168.20.25
D. IP address: 192.168.20.30
Subnet Mask: 255.255.255.240
Default Gateway: 192.168.20.17
E. IP address: 192.168.20.30 Subnet Mask: 255.255.255.240
Default Gateway: 192.168.20.25
Explanation/Reference:
For the 192.168.20.24/29 network, the usable hosts are 192.168.24.25 (router) ?192.168.24.30 (used for the sales server).
74. Which subnet mask would be appropriate for a network address range to be subnetted for up to eight LANs, with each LAN containing 5 to 26 hosts?
A. 0.0.0.240
B. 255.255.255.252
C. 255.255.255.0
D. 255.255.255.224
E. 255.255.255.240
Explanation/Reference:
For a class C network, a mask of 255.255.255.224 will allow for up to 8 networks with 32 IP addresses each (30 usable).
75. How many bits are contained in each field of an IPv6 address?
A. 24
B. 4
C. 8
D. 16
Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
76. What are three approaches that are used when migrating from an IPv4 addressing scheme to an IPv6 scheme. (Choose three.)
A. enable dual-stack routing
B. configure IPv6 directly
C. configure IPv4 tunnels between IPv6 islands
D. use proxying and translation to translate IPv6 packets into IPv4 packets
E. statically map IPv4 addresses to IPv6 addresses
F. use DHCPv6 to map IPv4 addresses to IPv6 addresses
Explanation/Reference:
Several methods are used terms of migration including tunneling, translators, and dual stack. Tunnels are used to carry one protocol inside another, while translators simply translate IPv6 packets into IPv4 packets. Dual stack uses a combination of both native IPv4 and IPv6. With dual stack, devices are able to run IPv4 and IPv6 together and if IPv6 communication is possible that is the preferred protocol. Hosts can simultaneously reach IPv4 and IPv6 content.
77. Refer to the exhibit. In this VLSM addressing scheme, what summary address would be sent from router A?
A. 172.16.0.0 /16
B. 172.16.0.0 /20
C. 172.16.0.0 /24
D. 172.32.0.0 /16
E. 172.32.0.0 /17
F. 172.64.0.0 /16
Explanation/Reference:
Router A receives 3 subnets: 172.16.64.0/18, 172.16.32.0/24 and 172.16.128.0/18. All these 3 subnets have the same form of 172.16.x.x so our summarized subnet must be also in that form -> Only A, B or . The smallest subnet mask of these 3 subnets is /18 so our summarized subnet must also have its subnet mask equal or smaller than /18. -> Only answer A has these 2 conditions -> .
78. How is an EUI-64 format interface ID created from a 48-bit MAC address?
A. by appending 0xFF to the MAC address
B. by prefixing the MAC address with 0xFFEE
C. by prefixing the MAC address with 0xFF and appending 0xFF to it
D. by inserting 0xFFFE between the upper three bytes and the lower three bytes of the MAC address E. by prefixing the MAC address with 0xF and inserting 0xF after each of its first three bytes
Explanation/Reference:
The modified EUI-64 format interface identifier is derived from the 48-bit link-layer (MAC) address by inserting the hexadecimal number FFFE between the upper three bytes (OUI field) and the lower three bytes (serial number) of the link layer address.
79. Refer to the exhibit. What is the most efficient summarization that R1 can use to advertise its networks to R2?
A. 172.1.0.0/22
B. 172.1.0.0/21
C. 172.1.4.0/22
D. 172.1.4.0/24
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24
E. 172.1.4.0/25
172.1.4.128/25
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24
Explanation/Reference:
The 172.1.4.0/22 subnet encompasses all routes from the IP range 172.1.4.0 ?172.1.7.255.
80. Which option is a valid IPv6 address?
A. 2001:0000:130F::099a::12a
B. 2002:7654:A1AD:61:81AF:CCC1
C. FEC0:ABCD:WXYZ:0067::2A4
D. 2004:1:25A4:886F::1
Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.
81. Which three are characteristics of an IPv6 anycast address? (Choose three.)
A. one-to-many communication model
B. one-to-nearest communication model
C. any-to-many communication model
D. a unique IPv6 address for each device in the group E. the same address for multiple devices in the group
F. delivery of packets to the group interface that is closest to the sending device
Explanation/Reference:
A new address type made specifically for IPv6 is called the Anycast Address. These IPv6 addresses are global addresses, these addresses can be assigned to more than one interface unlike an IPv6 unicast address. Anycast is designed to send a packet to the nearest interface that is apart of that anycast group.
The sender creates a packet and forwards the packet to the anycast address as the destination address which goes to the nearest router. The nearest router or interface is found by using the metric of a routing protocol currently running on the network. However in a LAN setting the nearest interface is found depending on the order the neighbors were learned. The anycast packet in a LAN setting forwards the packet to the neighbor it learned about first.
82. A national retail chain needs to design an IP addressing scheme to support a nationwide network. The company needs a minimum of 300 sub-networks and a maximum of 50 host addresses per subnet. Working with only one Class B address, which of the following subnet masks will support an appropriate addressing scheme? (Choose two.)
A. 255.255.255.0
B. 255.255.255.128
C. 255.255.252.0
D. 255.255.255.224
E. 255.255.255.192
F. 255.255.248.0
Explanation/Reference:
Subnetting is used to break the network into smaller more efficient subnets to prevent excessive rates of Ethernet packet collision in a large network. Such subnets can be arranged hierarchically, with the organization’s network address space (see also Autonomous System) partitioned into a tree-like structure. Routers are used to manage traffic and constitute borders between subnets. A routing prefix is the sequence of leading bits of an IP address that precede the portion of the address used as host identifier. In
IPv4 networks, the routing prefix is often expressed as a “subnet mask”, which is a bit mask covering the number of bits used in the prefix. An IPv4 subnet mask is frequently expressed in quad-dotted decimal representation, e.g., 255.255.255.0 is the subnet mask for the 192.168.1.0 network with a 24-bit routing prefix (192.168.1.0/24).
83. Refer to the exhibit. A network administrator is adding two new hosts to Switch A . Which three values could be used for the configuration of these hosts? (Choose three.)
A. host A IP address: 192.168.1.79
B. host A IP address: 192.168.1.64
C. host A default gateway: 192.168.1.78
D. host B IP address: 192.168.1.128
E. host B default gateway: 192.168.1.129
F. host B IP address: 192.168.1.190
84. Which IPv6 address is the all-router multicast group?
A. FF02::1
B. FF02::2
C. FF02::3
D. FF02::4
Explanation/Reference:
Well-known IPv6 multicast addresses:
Address Description
ff02::1
All nodes on the local network segment ff02::2
All routers on the local network segment
85. Refer to the exhibit. Which address range efficiently summarizes the routing table of the addresses for router Main?
A. 172.16.0.0/21
B. 172.16.0.0/20
C. 172.16.0.0/16
D. 172.16.0.0/18
Explanation/Reference:
The 172.16.0.0./20 network is the best option as it includes all networks from 172.16.0.0 – 172.16.16.0 and does it more efficiently than the /16 and /18 subnets. The /21 subnet will not include all the other subnets in this one single summarized address.
86. Which IPv6 address is valid
A. 2001:0db8:0000:130F:0000:0000:08GC:140B
B. 2001:0db8:0:130H::87C:140B
C. 2031::130F::9C0:876A:130B
D. 2031:0:130F::9C0:876A:130B
Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.
87. Which command can you use to manually assign a static IPv6 address to a router interface?
A. ipv6 autoconfig 2001:db8:2222:7272::72/64
B. ipv6 address 2001:db8:2222:7272::72/64
C. ipv6 address PREFIX_1 ::1/64
D. ipv6 autoconfig
ExplanationExplanation/Reference:
To assign an IPv6 address to an interface, use the “ipv6 address” command and specify the IP address you
wish to use.
88. Which of these represents an IPv6 link-local address?
A. FE80::380e:611a:e14f:3d69
B. FE81::280f:512b:e14f:3d69
C. FEFE:0345:5f1b::e14d:3d69
D. FE08::280e:611:a:f14f:3d69
Explanation/Reference:
In the Internet Protocol Version 6 (IPv6), the address block fe80::/10 has been reserved for link- local unicast addressing. The actual link local addresses are assigned with the prefix fe80::/64. They may be assigned by automatic (stateless) or stateful (e.g. manual) mechanisms.
89. The network administrator is asked to configure 113 point-to-point links. Which IP addressing scheme defines the address range and subnet mask that meet the requirement and waste the fewest subnet and host addresses?
A. 10.10.0.0/16 subnetted with mask 255.255.255.252
B. 10.10.0.0/18 subnetted with mask 255.255.255.252
C. 10.10.1.0/24 subnetted with mask 255.255.255.252
D. 10.10.0.0/23 subnetted with mask 255.255.255.252
E. 10.10.1.0/25 subnetted with mask 255.255.255.252
Explanation/Reference:
We need 113 point-to-point links which equal to 113 sub-networks < 128 so we need to borrow 7 bits (because 2^7 = 128).
The network used for point-to-point connection should be /30. So our initial network should be 30 ?7 = 23. So 10.10.0.0/23 is the correct answer.
You can understand it more clearly when writing it in binary form:
/23 = 1111 1111.1111 1110.0000 0000
/30 = 1111 1111.1111 1111.1111 1100 (borrow 7 bits)
90. A Cisco router is booting and has just completed the POST process. It is now ready to find and load an IOS image. What function does the router perform next?
A. It checks the configuration register.
B. It attempts to boot from a TFTP server.
C. It loads the first image file in flash memory.
D. It inspects the configuration file in NVRAM for boot instructions.
Explanation/Reference:
Default (normal) Boot SequencePower on Router – Router does POST – Bootstrap starts IOS load – Check configuration registerto see what mode the router should boot up in (usually 0x2102 to read startup-config in NVRAM / or 0x2142 to start in “setup-mode”) – check the startup-config file in NVRAM for boot-system commands – load IOS from Flash.
91.Refer to the exhibit. What is the meaning of the output MTU 1500 bytes?
A. The maximum number of bytes that can traverse this interface per second is 1500.
B. The minimum segment size that can traverse this interface is 1500 bytes.
C. The maximum segment size that can traverse this interface is 1500 bytes.
D. The minimum packet size that can traverse this interface is 1500 bytes.
E. The maximum packet size that can traverse this interface is 1500 bytes.
F. The maximum frame size that can traverse this interface is 1500 bytes.
Explanation/Reference:
The Maximum Transmission Unit (MTU) defines the maximum Layer 3 packet (in bytes) that the layer can pass onwards.
92. On a corporate network, hosts on the same VLAN can communicate with each other, but they are unable to communicate with hosts on different VLANs. What is needed to allow communication between the VLANs?
A. a router with subinterfaces configured on the physical interface that is connected to the switch
B. router with an IP address on the physical interface connected to the switch
C. a switch with an access link that is configured between the switches
D. a switch with a trunk link that is configured between the switches
Explanation/Reference:
Different VLANs can’t communicate with each other , they can communicate with the help of Layer3 router. Hence , it is needed to connect a router to a switch , then make the sub-interface on the router to connect to the switch, establishing Trunking links to achieve communications of devices which belong to different VLANs.
When using VLANs in networks that have multiple interconnected switches, you need to use VLAN trunking between the switches. With VLAN trunking, the switches tag each frame sent between switches so that the receiving switch knows to what VLAN the frame belongs. End user devices connect to switch ports that provide simple connectivity to a single VLAN each. The attached devices are unaware of any VLAN structure.
By default, only hosts that are members of the same VLAN can communicate. To change this and allow inter-VLAN communication, you need a router or a layer 3 switch. Here is the example of configuring the router for inter-vlan communication RouterA(config)#int f0/0.1
RouterA(config-subif)#encapsulation ? dot1Q IEEE 802.1Q Virtual LAN
RouterA(config-subif)#encapsulation dot1Q or isl VLAN ID RouterA(config-subif)# ip address x.x.x.x y.y.y.y
93. Which command displays CPU utilization?
A. show protocols
B. show process
C. show system
D. show version
Explanation/Reference:
The “show process” (in fact, the full command is “show processes”) command gives us lots of information about each process but in fact it is not easy to read. Below shows the output of this command (some next pages are omitted)
A more friendly way to check the CPU utilization is the command “show processes cpu history”, in which the total
CPU usage on the router over a period of time: one minute, one hour, and 72 hours are clearly shown
+ The Y- axis of the graph is the CPU utilization.+ The X-axis of the graph is the increment within the period displayed in the graph. For example, from the last graph (last 72 hours) we learn that the highest CPU utilization within 72 hours is 37% about six hours ago.
94. What two things will a router do when running a distance vector routing protocol? (Choose two.)
A. Send periodic updates regardless of topology changes.
B. Send entire routing table to all routers in the routing domain.
C. Use the shortest-path algorithm to the determine best path.
D. Update the routing table based on updates from their neighbors.
E. Maintain the topology of the entire network in its database.
Explanation/Reference:
Distance means how far and Vector means in which direction. Distance Vector routing protocols passperiodic copies of routing table to neighbor routers and accumulate distance vectors. In distance vector routing protocols, routers discover the best path to destination from each neighbor. The routing updates proceed step by step from router to router.
95. Which command is used to display the collection of OSPF link states?
A. show ip ospf link-state
B. show ip ospf lsa database
C. show ip ospf neighbors
D. show ip ospf database
Explanation/Reference:
The “show ip ospf database” command displays the link states. Here is an example:
Here is the lsa database on R2.
R2#show ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count2.2.2.2 2.2.2.2 793 0x80000003 0x004F85
210.4.4.4 10.4.4.4 776 0x80000004 0x005643 1111.111.111.111 111.111.111.111 755
0x80000005 0x0059CA 2133.133.133.133 133.133.133.133 775 0x80000005 0x00B5B1 2 Net
Link States (Area 0)
Link ID ADV Router Age Seq# Checksum10.1.1.1 111.111.111.111 794 0x80000001
0x001E8B10.2.2.3 133.133.133.133 812 0x80000001 0x004BA910.4.4.1 111.111.111.111 755
0x80000001 0x007F1610.4.4.3 133.133.133.133 775 0x80000001 0x00C31F
96. Refer to the exhibit. The technician wants to upload a new IOS in the router while keeping the existing IOS. What is the maximum size of an IOS file that could be loaded if the original IOS is also kept in flash?
A. 3 MB
B. 4 MB
C. 5 MB
D. 7 MB
E. 8 MB
Explanation/Reference:
In this example, there are a total of 8 MB, but 3.8 are being used already, so another file as large as 4MB can be loaded in addition to the original file.
97. If IP routing is enabled, which two commands set the gateway of last resort to the default gateway? (Choose two.)
A. ip default-gateway 0.0.0.0
B. ip route 172.16.2.1 0.0.0.0 0.0.0.0
C. ip default-network 0.0.0.0
D. ip default-route 0.0.0.0 0.0.0.0 172.16.2.1
E. ip route 0.0.0.0 0.0.0.0 172.16.2.1
Explanation/Reference:
Both the “ip default-network” and “ip route 0.0.0.0 0.0.0.0 (next hop)” commands can be used to set the
default gateway in a Cisco router.
98. Refer to the exhibit. The two exhibited devices are the only Cisco devices on the network. The serial network between the two devices has a mask of 255.255.255.252. Given the output that is shown, what three statements are true of these devices? (Choose three.)
A. The Manchester serial address is 10.1.1.1.
B. The Manchester serial address is 10.1.1.2.
C. The London router is a Cisco 2610.
D. The Manchester router is a Cisco 2610.
E. The CDP information was received on port Serial0/0 of the Manchester router.
F. The CDP information was sent by port Serial0/0 of the London router.
Explanation/Reference:
From the output, we learn that the IP address of the neighbor router is 10.1.1.2 and the question stated that the subnet mask of the network between two router is 255.255.255.252. Therefore there are only 2 available hosts in this network (22 ?2 = 2). So we can deduce the ip address (of the serial interface) of Manchester router is 10.1.1.1 -> The platform of the neighbor router is cisco 2610, as shown in the output – > Maybe the most difficult choice of this question is the answer E or F. Please notice that “Interface” refers to the local port on the local router, in this case it is the port of Manchester router, and “Port ID (outgoing port)” refers to the port on the neighbor router.
99. Which parameter would you tune to affect the selection of a static route as a backup, when a dynamic protocol is also being used?
A. hop count
B. administrative distance
C. link bandwidth
D. link delay
E. link cost
Explanation/Reference:
By default the administrative distance of a static route is 1, meaning it will be preferred over all dynamic routing protocols. If you want to have the dynamic routing protocol used and have the static route be used only as a backup, you need to increase the AD of the static route so that it is higher than the dynamic routing protocol.
100. Refer to the exhibit. A network associate has configured OSPF with the command:
City(config-router)# network 192.168.12.64 0.0.0.63 area 0
After completing the configuration, the associate discovers that not all the interfaces are participating in
OSPF. Which three of the interfaces shown in the exhibit will participate in OSPF according to this
configuration statement? (Choose three.)
A. FastEthernet0 /0
B. FastEthernet0 /1
C. Serial0/0
D. Serial0/1.102
E. Serial0/1.103
F. Serial0/1.104
Explanation/Reference:
The “network 192.168.12.64 0.0.0.63 equals to network 192.168.12.64/26. This network has: + Increment:
64 (/26= 1111 1111.1111 1111.1111 1111.1100 0000) + Network address: 192.168.12.64
+ Broadcast address: 192.168.12.127
Therefore all interface in the range of this network will join OSPF.
101. Refer to the exhibit. The Lakeside Company has the internetwork in the exhibit. The administrator would like to reduce the size of the routing table on the Central router. Which partial routing table entry in the Central router represents a route summary that represents the LANs in Phoenix but no additional subnets?
A. 10.0.0.0/22 is subnetted, 1 subnets
D 10.0.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
B. 10.0.0.0/28 is subnetted, 1 subnets
D 10.2.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
C. 10.0.0.0/30 is subnetted, 1 subnets
D 10.2.2.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
D. 10.0.0.0/22 is subnetted, 1 subnets
D 10.4.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
E. 10.0.0.0/28 is subnetted, 1 subnets
D. 10.4.4.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
F. 10.0.0.0/30 is subnetted, 1 subnets
D 10.4.4.4 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
Explanation/Reference:
The 10.4.0.0/22 route includes 10.4.0.0/24, 10.4.1.0/24, 10.4.2.0/24 and 10.4.3.0/24 only.
102. Refer to the graphic. A static route to the 10.5.6.0/24 network is to be configured on the HFD router. Which
commands will accomplish this? (Choose two.)
A. HFD(config)# ip route 10.5.6.0 0.0.0.255 fa0/0
B. HFD(config)# ip route 10.5.6.0 0.0.0.255 10.5.4.6
C. HFD(config)# ip route 10.5.6.0 255.255.255.0 fa0/0
D. HFD(config)# ip route 10.5.6.0 255.255.255.0 10.5.4.6
E. HFD(config)# ip route 10.5.4.6 0.0.0.255 10.5.6.0
F. HFD(config)# ip route 10.5.4.6 255.255.255.0 10.5.6.0
Explanation/Reference:
The simple syntax of static route: ip route destination-network-address subnet-mask {next-hop-IP-address | exit-interface} + destination-network-address: destination network address of the remote network + subnet mask: subnet mask of the destination network + next-hop-IP-address: the IP address of the receiving interface on the next-hop router + exit-interface: the local interface of this router where the packets will go out In the statement “ip route 10.5.6.0 255.255.255.0 fa0/0:
+ 10.5.6.0 255.255.255.0: the destination network
+fa0/0: the exit-interface
103. Before installing a new, upgraded version of the IOS, what should be checked on the router, and which command should be used to gather this information? (Choose two.)
A. the amount of available ROM
B. the amount of available flash and RAM memory
C. the version of the bootstrap software present on the router D. show version
D. show processes
E. show running-config
Explanation/Reference:
When upgrading new version of the IOS we need to copy the IOS to the Flash so first we have to check if the Flash has enough memory or not. Also running the new IOS may require more RAM than the older one so we should check the available RAM too. We can check both with the “show version” command.
104. Which command reveals the last method used to powercycle a router?
A. show reload
B. show boot
C. show running-config
D. show version
Explanation/Reference:
The “show version” command can be used to show the last method to powercycle (reset) a router
105. Which command would you use on a Cisco router to verify the Layer 3 path to a host?
A. tracert address
B. traceroute address
C. telnet address
D. ssh address
Explanation/Reference:
In computing, traceroute is a computer network diagnostic tool for displaying the route (path) and measuring transit delays of packets across an Internet Protocol (IP) network. The history of the route is recorded as the round-trip times of the packets received from each successive host (remote node) in the route (path); the sum of the mean times in each hop indicates the total time spent to establish the connection. Traceroute proceeds unless all (three) sent packets are lost more than twice, then the connection is lost and the route cannot be evaluated. Ping, on the other hand, only computes the final round-trip times from the destination point.
106. What information does a router running a link-state protocol use to build and maintain its topological database? (Choose two.)
A. hello packets
B. SAP messages sent by other routers
C. LSAs from other routers
D. beacons received on point-to-point links
E. routing tables received from other link-state routers
F. TTL packets from designated routers
Explanation/Reference:
Neighbor discovery is the first step in getting a link state environment up and running. In keeping with the friendly neighbor terminology, a Hello protocol is used for this step. The protocol will define a Hello packet format and a procedure for exchanging the packets and processing the information the packets contain.
After the adjacencies are established, the routers may begin sending out LSAs. As the term flooding implies, the advertisements are sent to every neighbor. In turn, each received LSA is copied and forwarded to every neighbor except the one that sent the LSA.
107. Which statements describe the routing protocol OSPF? (Choose three.)
A. It supports VLSM.
B. It is used to route between autonomous systems.
C. It confines network instability to one area of the network.
D. It increases routing overhead on the network.
E. It allows extensive control of routing updates.
F. It is simpler to configure than RIP v2.
Explanation/Reference:
The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth.
OSPF uses flooding to exchange link-state updates between routers. Any change in routing information is flooded to all routers in the network. Areas are introduced to put a boundary on the explosion of link-state updates. Flooding and calculation of the Dijkstra algorithm on a router is limited to changes within an area.
108. Refer to the exhibit. A network administrator configures a new router and enters the copy startupconfig running-config command on the router. The network administrator powers down the router and sets it up at a remote location. When the router starts, it enters the system configuration dialog as shown. What is the cause of the problem?
A. The network administrator failed to save the configuration.
B. The configuration register is set to 0x2100.
C. The boot system flash command is missing from the configuration.
D. The configuration register is set to 0x2102.
E. The router is configured with the boot system startup command.
Explanation/Reference:
The “System Configuration Dialog” appears only when no startup configuration file is found. The network administrator has made a mistake because the command “copy startup-config running- config” will copy the startup config (which is empty) over the running config (which is configured by the administrator). So everything configured was deleted. Note: We can tell the router to ignore the start-up configuration on the next reload by setting the register to 0?142. This will make the “System Configuration Dialog” appear at the next reload.
109. Refer to the exhibit. Which WAN protocol is being used?
A. ATM
B. HDLC
C. Frame-relay
D. PPP
Explanation/Reference:
This question is to examine the show int command. According to the information provided in the exhibit, we can know that the data link protocol used in this network is the Frame Relay protocol. “LMI enq sent…”
110. What is the default administrative distance of OSPF?
A. 90
B. 100
C. 110
D. 120
Explanation/Reference:
Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value. Default Distance Value Table This table lists the administrative distance default values of the protocols that Cisco supports:
Route Source
Default Distance Values
Connected interface
Static route
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route External Border Gateway Protocol
(BGP)
Internal EIGRP
IGRP
OSPF
Intermediate System-to-Intermediate System (IS-IS)
Routing Information Protocol (RIP)
Exterior Gateway Protocol (EGP)
On Demand Routing (ODR)
External EIGRP
Internal BGP
Unknown*
111. Which characteristics are representative of a link-state routing protocol? (Choose three.)
A. provides common view of entire topology
B. exchanges routing tables with neighbors
C. calculates shortest path
D. utilizes event-triggered updates
E. utilizes frequent periodic updates
Explanation/Reference:
Each of routers running link-state routing protocol learns paths to all the destinations in its “area” so we can say although it is a bit unclear.
Link-state routing protocols generate routing updates only (not the whole routing table) when a change occurs in the network topology so Link-state routing protocol like OSPF uses Dijkstra algorithm to calculate the shortest path -> . Unlike
Distance vector routing protocol (which utilizes frequent periodic updates), link-state routing protocol utilizes event-triggered updates (only sends update when a change occurs) ->
112. Refer to the exhibit. Based on the exhibited routing table, how will packets from a host within the 192.168.10.192/26 LAN be forwarded to 192.168.10.1?
A. The router will forward packets from R3 to R2 to R1.
B. The router will forward packets from R3 to R1 to R2.
C. The router will forward packets from R3 to R2 to R1 AND from R3 to R1.
D. The router will forward packets from R3 to R1.
Explanation/Reference:
From the routing table we learn that network 192.168.10.0/30 is learned via 2 equal-cost paths (192.168.10.9 &192.168.10.5) -> traffic to this network will be load-balancing.
113. Refer to the exhibit. C-router is to be used as a “router-on-a-stick” to route between the VLANs. All the interfaces have been properly configured and IP routing is operational. The hosts in the VLANs have been configured with the appropriate default gateway. What is true about this configuration?
A. These commands need to be added to the configuration:
C-router(config)# router eigrp 123
C-router(config-router)# network 172.19.0.0
B. These commands need to be added to the configuration:
C-router(config)# router ospf 1
C-router(config-router)# network 172.19.0.0 0.0.3.255 area 0
C. These commands need to be added to the configuration:
C-router(config)# router rip
C-router(config-router)# network 172.19.0.0
D. No further routing configuration is required.
114. Which command would you configure globally on a Cisco router that would allow you to view directly connected Cisco devices?
A. enable cdp
B. cdp enable
C. cdp run
D. run cdp
Explanation/Reference:
CDP is enabled on Cisco routers by default. If you prefer not to use the CDP capability, disable it with the no cdp run command. In order to reenable CDP, use the cdp run command in global configuration mode. The “cdp enable” command is an interface command, not global.
115. Refer to the exhibit. Why is flash memory erased prior to upgrading the IOS image from the TFTP server?
A. The router cannot verify that the Cisco IOS image currently in flash is valid.
B. Flash memory on Cisco routers can contain only a single IOS image.
C. Erasing current flash content is requested during the copy dialog.
D. In order for the router to use the new image as the default, it must be the only IOS image in flash.
Explanation/Reference:
During the copy process, the router asked “Erasing flash before copying? [confirm]” and the administrator confirmed (by pressing Enter) so the flash was deleted. Note: In this case, the flash has enough space to copy a new IOS without deleting the current one. The current IOS is deleted just because the administrator wants to do so. If the flash does not have enough space you will see an error message like this: %Error copying tftp://192.168.2.167/ c1600-k8sy-mz.l23-16a.bin (Not enough space on device)
116. Refer to the exhibit. According to the routing table, where will the router send a packet destined for 10.1.5.65?
A. 10.1.1.2
B. 10.1.2.2
C. 10.1.3.3
D. 10.1.4.4
Explanation/Reference:
The destination IP address 10.1.5.65 belongs to 10.1.5.64/28, 10.1.5.64/29 & 10.1.5.64/27 subnets but the “longest prefix match” algorithm will choose the most specific subnet mask -> the prefix “/29 will be chosen to route the packet. Therefore the next-hop should be 10.1.3.3 -> .
117. Refer to the exhibit. Which address and mask combination represents a summary of the routes learned by EIGRP?
A. 192.168.25.0 255.255.255.240
B. 192.168.25.0 255.255.255.252
C. 192.168.25.16 255.255.255.240
D. 192.168.25.16 255.255.255.252
E. 192.168.25.28 255.255.255.240
F. 192.168.25.28 255.255.255.252
Explanation/Reference:
The binary version of 20 is 10100.
The binary version of 16 is 10000.
The binary version of 24 is 11000.
The binary version of 28 is 11100.
The subnet mask is /28. The mask is 255.255.255.240.
Note: From the output above, EIGRP learned 4 routes and we need to find out the summary of them:
+ 192.168.25.16
+ 192.168.25.20
+ 192.168.25.24
+ 192.168.25.28
-> The increment should bE. 28 ?16 = 12 but 12 is not an exponentiation of 2 so we must choose 16 (24).
Therefore the subnet mask is /28 (=1111 1111.1111 1111.1111 1111.11110000) = 255.255.255.240
So the best answer should be 192.168.25.16 255.255.255.240
118. Refer to the exhibit. Assuming that the entire network topology is shown, what is the operational status of the interfaces of R2 as indicated by the command output shown?
A. One interface has a problem.
B. Two interfaces have problems.
C. The interfaces are functioning correctly.
D. The operational status of the interfaces cannot be determined from the output shown.
Explanation/Reference:
The output shown shows normal operational status of the router’s interfaces. Serial0/0 is down because it has been disabled using the “shutdown” command.
119. Which two locations can be configured as a source for the IOS image in the boot system command? (Choose two.)
A. RAM
B. NVRAM
C. flash memory
D. HTTP server
E. TFTP server
F. Telnet server
Explanation/Reference:
The following locations can be configured as a source for the IOS image:
+ Flash (the default location)
+ TFTP server
+ ROM (used if no other source is found)
120. Refer to the exhibit. Given the output for this command, if the router ID has not been manually set, what router ID will OSPF use for this router?
A. 10.1.1.2
B. 10.154.154.1
C. 172.16.5.1
D. 192.168.5.3
Explanation/Reference:
The highest IP address of all loopback interfaces will be chosen -> Loopback 0 will be chosen as the router
ID.
121. Which two statements describe the process identifier that is used in the command to configure OSPF on a router? (Choose two.) Router(config)# router ospf 1
A. All OSPF routers in an area must have the same process ID
B. Only one process number can be used on the same router.
C. Different process identifiers can be used to run multiple OSPF processes
D. The process number can be any number from 1 to 65,535.
E. Hello packets are sent to each neighbor to determine the processor identifier.
Explanation/Reference:
Multiple OSPF processes can be configured on a router using multiple process ID’s.
The valid process ID’s are shown below:
Edge-B(config)#router ospf ?
<1-65535> Process ID
122. Refer to the exhibit. What commands must be configured on the 2950 switch and the router to allow communication between host 1 and host 2? (Choose two.)
A. Router(config)# interface fastethernet 0/0
Router(config-if)# ip address 192.168.1.1 255.255.255.0 Router(config-if)#
no shut down
B. Router(config)# interface fastethernet 0/0
Router(config-if)# no shut down
Router(config)# interface fastethernet 0/0.1
Router(config-subif)# encapsulation dot1q 10
Router(config-subif)# ip address 192.168.10.1 255.255.255.0
Router(config)# interface fastethernet 0/0.2
Router(config-subif)# encapsulation dot1q 20
Router(config-subif)# ip address 192.168.20.1 255.255.255.0
C. Router(config)# router eigrp 100
Router(config-router)# network 192.168.10.0
Router(config-router)# network 192.168.20.0
D. Switch1(config)# vlan database Switch1(config-vlan)# vtp domain XYZ
Switch1(config-vlan)# vtp server
E. Switch1(config)# interface fastethernet 0/1 Switch1(config-if)# switchport
mode trunk F. Switch1(config)# interface vlan 1 Switch1(config-if)# ip
default-gateway 192.168.1.1
Explanation/Reference:
The router will need to use subinterfaces, where each subinterface is assigned a VLAN and IP address for each VLAN. On the switch, the connection to the router need to be configured as a trunk using the switchport mode trunk command and it will need a default gateway for VLAN 1.
123. Refer to the exhibit. For what two reasons has the router loaded its IOS image from the location that is shown? (Choose two.)
A. Router1 has specific boot system commands that instruct it to load IOS from a TFTP server.
B. Router1 is acting as a TFTP server for other routers.
C. Router1 cannot locate a valid IOS image in flash memory.
D. Router1 defaulted to ROMMON mode and loaded the IOS image from a TFTP server.
E. Cisco routers will first attempt to load an image from TFTP for management purposes
Explanation/Reference:
The loading sequence of CISCO IOS is as follows:
Booting up the router and locating the Cisco IOS
POST (power on self test)
Bootstrap code executed
Check Configuration Register value (NVRAM) which can be modified using the config-register
command
= ROM Monitor mode
= ROM IOS
– 15 = startup-config in NVRAM
4. Startup-config filE. Check for boot system commands (NVRAM) If boot system commands in startup-config a. Run boot system commands in order they appear in startup-config to locate the IOS b. [If boot system commands fail, use default fallback sequence to locate the IOS (Flash, TFTP, ROM)?] If no boot system commands in startup-config use the default fallback sequence in locating the IOS:
Flash (sequential)
TFTP server (netboot)
ROM (partial IOS) or keep retrying TFTP depending upon router model
5. If IOS is loaded, but there is no startup-config file, the router will use the default fallback sequence for
locating the IOS and then it will enter setup mode or the setup dialogue.
124. Refer to the exhibit. What can be determined about the router from the console output?
A. No configuration file was found in NVRAM.
B. No configuration file was found in flash.
C. No configuration file was found in the PCMCIA card.
D. Configuration file is normal and will load in 15 seconds.
Explanation/Reference:
When no startup configuration file is found in NVRAM, the System Configuration Dialog will appear to ask if we want to enter the initial configuration dialog or not.
125. Which three elements must be used when you configure a router interface for VLAN trunking? (Choose three.)
A. one physical interface for each subinterface
B. one IP network or subnetwork for each subinterface
C. a management domain for each subinterface
D. subinterface encapsulation identifiers that match VLAN tags
E. one subinterface per VLAN
F. subinterface numbering that matches VLAN tags
Explanation/Reference:
This scenario is commonly called a router on a stick. A short, well written article on this operation can be
found here: http://www.thebryantadvantage.com/RouterOnAStickCCNACertificationExamTutorial.htm
126. Which commands are required to properly configure a router to run OSPF and to add network 192.168.16.0/24 to OSPF area 0? (Choose two.)
A. Router(config)# router ospf 0
B. Router(config)# router ospf 1
C. Router(config)# router ospf area 0
D. outer(config-router)# network 192.168.16.0 0.0.0.255 0
E. Router(config-router)# network 192.168.16.0 0.0.0.255 area 0
F. Router(config-router)# network 192.168.16.0 255.255.255.0 area 0
Explanation/Reference:
In the router ospf command, the ranges from 1 to 65535 so o is an invalid number -> but To configure OSPF, we need a wildcard in the “network” statement, not a subnet mask. We also need to assgin an area to this process ->
127. A router receives information about network 192.168.10.0/24 from multiple sources. What will the router consider the most reliable information about the path to that network?
A. a directly connected interface with an address of 192.168.10.254/24
B. a static route to network 192.168.10.0/24
C. a RIP update for network 192.168.10.0/24
D. an OSPF update for network 192.168.0.0/16
E. a default route with a next hop address of 192.168.10.1
F. a static route to network 192.168.10.0/24 with a local serial interface configured as the next hop
Explanation/Reference:
When there is more than one way to reach a destination, it will choose the best one based on a couple of things. First, it will choose the route that has the longest match; meaning the most specific route. So, in this case the /24 routes will be chosen over the /16 routes. Next, from all the /24 routes it will choose the one with the lowest administrative distance. Directly connected routes have an AD of 1 so this will be the route
chosen.
128. What is the default maximum number of equal-cost paths that can be placed into the routing table of aCisco OSPF router?
A. 2
B. 4
C. 16
D. unlimited
Explanation/Reference:
maximum-paths (OSPF) To control the maximum number of parallel routes that Open Shortest Path First (OSPF) can support, use the maximum-paths command. Syntax Description maximum Maximum number of parallel routes that OSPF can install in a routing table. The range is from 1 to 16
routes.
Command Default
8 paths
129. Which command shows your active Telnet connections?
A. show cdp neigbors
B. show session
C. show users
D. show vty logins
Explanation/Reference:
The “show users” shows telnet/ssh connections to your router while “show sessions” shows telnet/ssh connections from your router (to other devices). The question asks about “your active Telnet connections”, meaning connections from your router so the answer should be A.
130. Refer to the exhibit. What statement is true of the configuration for this network?
A. The configuration that is shown provides inadequate outside address space for translation of the
number of inside addresses that are supported.
B. Because of the addressing on interface FastEthernet0/1, the Serial0/0 interface address will not support
the NAT configuration as shown.
C. The number 1 referred to in the ip nat inside source command references access-list number 1.
D. ExternalRouter must be configured with static routes to networks 172.16.1.0/24 and 172.16.2.0/24.
131. Which type of EIGRP route entry describes a feasible successor?
A. a backup route, stored in the routing table
B. a primary route, stored in the routing table
C. a backup route, stored in the topology table
D. a primary route, stored in the topology table
Explanation/Reference:
EIGRP uses the Neighbor Table to list adjacent routers. The Topology Table list all the learned routers to destination whilst the Routing Table contains the best route to a destination, which is known as the Successor. The Feasible Successor is a backup route to a destination which is kept in the Topology Table.
132. Which statement describes the process of dynamically assigning IP addresses by the DHCP server?
A. Addresses are allocated after a negotiation between the server and the host to determine the length of
the agreement.
B. Addresses are permanently assigned so that the hosts uses the same address at all times.
C. Addresses are assigned for a fixed period of time, at the end of the period, a new request for an
address must be made.
D. Addresses are leased to hosts, which periodically contact the DHCP server to renew the lease.
133. What are two benefits of using NAT? (Choose two.)
A. NAT facilitates end-to-end communication when IPsec is enabled.
B. NAT eliminates the need to re-address all hosts that require external access.
C. NAT conserves addresses through host MAC-level multiplexing.
D. Dynamic NAT facilitates connections from the outside of the network.
E. NAT accelerates the routing process because no modifications are made on the packets
F. NAT protects network security because private networks are not advertised.
Explanation/Reference:
By not revealing the internal Ip addresses, NAT adds some security to the inside network -> F is correct.
NAT has to modify the source IP addresses in the packets -> E is not correct.
Connection from the outside of the network through a “NAT” network is more difficult than a more network because IP addresses of inside hosts are hidden -> C is not correct.
In order for IPsec to work with NAT we need to allow additional protocols, including Internet Key Exchange
(IKE), Encapsulating Security Payload (ESP) and Authentication Header (AH) -> more complex -> A is not
correct.
By allocating specific public IP addresses to inside hosts, NAT eliminates the need to re-address the inside
hosts -> B is correct.
NAT does conserve addresses but not through host MAC-level multiplexing. It conserves addresses by allowing many private IP addresses to use the same public IP address to go to the Internet -> C is not correct.
134. On which options are standard access lists based?
A. destination address and wildcard mask
B. destination address and subnet mask
C. source address and subnet mask
D. source address and wildcard mask
Explanation/Reference:
Standard ACL’s only examine the source IP address/mask to determine if a match is made. Extended ACL’s examine the source and destination address, as well as port information.
135. A network engineer wants to allow a temporary entry for a remote user with a specific username and password so that the user can access the entire network over the Internet. Which ACL can be used?
A. standard
B. extended
C. dynamic
D. reflexive
Explanation/Reference:
We can use a dynamic access list to authenticate a remote user with a specific username and password.
The authentication process is done by the router or a central access server such as a TACACS+ or RADIUS server. The configuration of dynamic ACL can be read here: http://www.cisco.com/en/US/tech/tk583/tk822/technologies_tech_note09186a0080094524.shtml
136.How does a DHCP server dynamically assign IP addresses to hosts?
A. Addresses are permanently assigned so that the host uses the same address at all times.
B. Addresses are assigned for a fixed period of time. At the end of the period, a new request for an
address must be made, and another address is then assigned.
C. Addresses are leased to hosts. A host will usually keep the same address by periodically contacting thDHCP server to renew the lease.
D. Addresses are allocated after a negotiation between the server and the host to determine the length of
the agreement.
Explanation/Reference:
DHCP works in a client/server mode and operates like any other client/server relationship. When a PC connects to a DHCP server, the server assigns or leases an IP address to that PC. The PC connects to the network with that leased IP address until the lease expires. The host must contact the DHCP server periodically to extend the lease. This lease mechanism ensures that hosts that move or power off do not hold onto addresses that they do not need. The DHCP server returns these addresses to the address pool and reallocates them as necessary.
137. Refer to the exhibit. Which rule does the DHCP server use when there is an IP address conflict?
A. The address is removed from the pool until the conflict is resolved.
B. The address remains in the pool until the conflict is resolved.
C. Only the IP detected by Gratuitous ARP is removed from the pool
D. Only the IP detected by Ping is removed from the pool.
E. The IP will be shown, even after the conflict is resolved.
Explanation/Reference:
An address conflict occurs when two hosts use the same IP address. During address assignment, DHCP checks for conflicts using ping and gratuitous ARP. If a conflict is detected, the address is removed from the pool. The address will not be assigned until the administrator resolves the conflict.
http://www.cisco.com/en/US/docs/ios/12_1/iproute/configuration/guide/1cddhcp.html
138. Which two tasks does the Dynamic Host Configuration Protocol perform? (Choose two.)
A. Set the IP gateway to be used by the network.
B. Perform host discovery used DHCPDISCOVER message.
C. Configure IP address parameters from DHCP server to a host.
D. Provide an easy management of layer 3 devices.
E. Monitor IP performance using the DHCP server.
F. Assign and renew IP address from the default pool.
Explanation/Reference:
The Dynamic Host Configuration Protocol (DHCP) is a network protocol used to configure devices that are connected to a network (known as hosts) so they can communicate on that network using the Internet Protocol (IP). It involves clients and a server operating in a clientserver model. DHCP servers assigns IP addresses from a pool of addresses and also assigns other parameters such as DNS and default gateways to hosts.
139, Refer to the exhibit. What statement is true of the configuration for this network?
A. The configuration that is shown provides inadequate outside address space for translation of the
number of inside addresses that are supported.
B. Because of the addressing on interface FastEthernet0/1, the Serial0/0 interface address will not support the NAT configuration as shown.
C. The number 1 referred to in the ip nat inside source command references access-list number 1.
D. ExternalRouter must be configured with static routes to networks 172.16.1.0/24 and 172.16.2.0/24.
140. When a DHCP server is configured, which two IP addresses should never be assignable to hosts? (Choose two.)
A. network or subnetwork IP address
B. broadcast address on the network
C. IP address leased to the LAN
D. IP address used by the interfaces
E. manually assigned address to the clients
F. designated IP address to the DHCP server
Explanation/Reference:
Network or subnetwork IP address (for example 11.0.0.0/8 or 13.1.0.0/16) and broadcast address (for example 23.2.1.255/24) should never be assignable to hosts. When try to assign these addresses to hosts, you will receive an error message saying that they can’t be assignable.
141. Which two statements about static NAT translations are true? (Choose two.)
A. They allow connections to be initiated from the outside.
B. They require no inside or outside interface markings because addresses are statically defined.
C. They are always present in the NAT table.
D. They can be configured with access lists, to allow two or more connections to be initiated from the
outside.
Explanation/Reference:
Static NAT is to map a single outside IP address to a single inside IP address. This is typically done to allow incoming connections from the outside (Internet) to the inside. Since these are static, they are always present in the NAT table even if they are not actively in use.
142. Which statement about access lists that are applied to an interface is true?
A. You can place as many access lists as you want on any interface.
B. You can apply only one access list on any interface.
C. You can configure one access list, per direction, per Layer 3 protocol.
D. You can apply multiple access lists with the same protocol or in different directions.
Explanation/Reference:
We can have only 1 access list per protocol, per direction and per interface. It means: + We can not have 2 inbound access lists on an interface + We can have 1 inbound and 1 outbound access list on an interface
143. Which item represents the standard IP ACL?
A. access-list 110 permit ip any any
B. access-list 50 deny 192.168.1.1 0.0.0.255
C. access list 101 deny tcp any host 192.168.1.1
D. access-list 2500 deny tcp any host 192.168.1.1 eq 22
Explanation/Reference:
The standard access lists are ranged from 1 to 99 and from 1300 to 1999 so only access list 50 is a standard access list.
144. A network administrator is configuring ACLs on a Cisco router, to allow traffic from hosts on networks 192.168.146.0, 192.168.147.0, 192.168.148.0, and 192.168.149.0 only. Which two ACL statements, when combined, would you use to accomplish this task? (Choose two.)
A. access-list 10 permit ip 192.168.146.0 0.0.1.255
B. access-list 10 permit ip 192.168.147.0 0.0.255.255
C. access-list 10 permit ip 192.168.148.0 0.0.1.255
D. access-list 10 permit ip 192.168.149.0 0.0.255.255
E. access-list 10 permit ip 192.168.146.0 0.0.0.255
F. access-list 10 permit ip 192.168.146.0 255.255.255.0
Explanation/Reference:
access-list 10 permit ip 192.168.146.0 0.0.1.255 will include the 192.168.146.0 and 192.168.147.0 subnets, while access-list 10 permit ip 192.168.148.0 0.0.1.255 will include
145. What can be done to secure the virtual terminal interfaces on a router? (Choose two.)
A. Administratively shut down the interface.
B. Physically secure the interface.
C. Create an access list and apply it to the virtual terminal interfaces with the access-group command.
D. Configure a virtual terminal password and login process.
E. Enter an access list and apply it to the virtual terminal interfaces using the access-class command.
Explanation/Reference:
It is a waste to administratively shut down the interface. Moreover, someone can still access the virtual terminal interfaces via other interfaces -> We can not physically secure a virtual interface because it is “virtual” -> To apply an access list to a virtual terminal interface we must use the “access-class” command. The “access-group” command is only used to apply an access list to a physical interface -> C is not correct. The most simple way to secure the virtual terminal interface is to configure a username & password to prevent unauthorized login.
146. Which two commands correctly verify whether port security has been configured on port FastEthernet 0/12 on a switch? (Choose two.)
A. SW1#show port-secure interface FastEthernet 0/12
B. SW1#show switchport port-secure interface FastEthernet 0/12
C. SW1#show running-config
D. SW1#show port-security interface FastEthernet 0/12
E. SW1#show switchport port-security interface FastEthernet 0/12
Explanation/Reference:
We can verify whether port security has been configured by using the “show running-config” or “show port- security interface ” for more detail. An example of the output of “show port-security interface ” command is shown below:
147. Refer to the exhibit. The following commands are executed on interface fa0/1 of 2950Switch.
2950Switch(config-if)# switchport port-security
2950Switch(config-if)# switchport port-security mac-address sticky
2950Switch(config-if)# switchport port-security maximum 1
The Ethernet frame that is shown arrives on interface fa0/1.
What two functions will occur when this frame is received by 2950Switch? (Choose two.)
A. The MAC address table will now have an additional entry of fa0/1 FFFF.FFFF.FFFF.
B. Only host A will be allowed to transmit frames on fa0/1.
C. This frame will be discarded when it is received by 2950Switch.
D. All frames arriving on 2950Switch with a destination of 0000.00aa.aaaa will be forwarded out fa0/1.
E. Hosts B and C may forward frames out fa0/1 but frames arriving from other switches will not be
forwarded out fa0/1.
F. Only frames from source 0000.00bb.bbbb, the first learned MAC address of 2950Switch, will be
Explanation/Reference:
The configuration shown here is an example of port security, specifically port security using sticky addresses. You can use port security with dynamically learned and static MAC addresses to restrict a port’s ingress traffic by limiting the MAC addresses that are allowed to send traffic into the port. When you assign secure MAC addresses to a secure port, the port does not forward ingress traffic that has source addresses outside the group of defined addresses. If you limit the number of secure MAC addresses to one and assign a single secure MAC address, the device attached to that port has the full bandwidth of the port. Port security with sticky MAC addresses provides many of the same benefits as port security with static MAC addresses, but sticky MAC addresses can be learned dynamically. Port security with sticky MAC addresses retains dynamically learned MAC addresses during a link-down condition.
148. What will be the result if the following configuration commands are implemented on a Cisco switch?
Switch(config-if)# switchport port-security
Switch(config-if)# switchport port-security mac-address sticky
A. A dynamically learned MAC address is saved in the startup-configuration file.
B. A dynamically learned MAC address is saved in the running-configuration file.
C. A dynamically learned MAC address is saved in the VLAN database.
D. Statically configured MAC addresses are saved in the startup-configuration file if frames from that
address are received.
E. Statically configured MAC addresses are saved in the running-configuration file if frames from that
address are received.
Explanation/Reference:
In the interface configuration mode, the command switchport port-security mac-address sticky enables sticky learning. When entering this command, the interface converts all the dynamic secure MAC addresses to sticky secure MAC addresses.
149. The network administrator cannot connect to Switch1 over a Telnet session, although the hosts attached to Switch1 can ping the interface Fa0/0 of the router. Given the information in the graphic and assuming that the router and Switch2 are configured properly, which of the following commands should be issued on Switch1 to correct this problem?
A. Switch1(config)# line con0
Switch1(config-line)# password cisco
Switch1(config-line)#login
B. Switch1(config)# interface fa0/1
Switch1(config-if)# ip address 192.168.24.3 255.255.255.0
C. Switch1(config)# ip default-gateway 192.168.24.1
D. Switch1(config)# interface fa0/1
Switch1(config-if)# duplex full
Switch1(config-if)# speed 100
E. Switch1(config)# interface fa0/1
Switch1(config-if)# switchport mode trunk
Explanation/Reference:
Since we know hosts can reach the router through the switch, we know that connectivity, duplex. Speed, etc. are good. However, for the switch itself to reach networks outside the local one, the ip default-gateway command must be used.
150. Refer to the exhibit. Which of these statements correctly describes the state of the switch once the boot process has been completed?
A. As FastEthernet0/12 will be the last to come up, it will be blocked by STP.
B. Remote access management of this switch will not be possible without configuration change.
C. More VLANs will need to be created for this switch.
D. The switch will need a different IOS code in order to support VLANs and STP.
Explanation/Reference:
Notice the line, which says “Interface VLAN1, changed state to administratively down”. This shows that VLAN1 is shut down. Hence remote management of this switch is not possible unless VLAN1 is brought back up. Since VLAN1 is the only interface shown in the output, you have to assume that no other VLAN interface has been configured with an IP Address.
151. Refer to exhibit. A network administrator cannot establish a Telnet session with the indicated router. What is the cause of this failure?
A. A Level 5 password is not set.
B. An ACL is blocking Telnet access.
C. The vty password is missing.
D. The console password is missing.
Explanation/Reference:
The login keyword has been set, but not password. This will result in the “password required, but none set” message to users trying to telnet to this router.
152. Refer to the exhibit. When running EIGRP, what is required for RouterA to exchange routing updates with RouterC?
A. AS numbers must be changed to match on all the routers
B. Loopback interfaces must be configured so a DR is elected
C. The no auto-summary command is needed on Router A and Router C
D. Router B needs to have two network statements, one for each connected network
Explanation/Reference:
This question is to examine the understanding of the interaction between EIGRP routers. The following information must be matched so as to create neighborhood. EIGRP routers to establish, must match the following information: 1. AS Number; 2. K value.
153. A router has two Fast Ethernet interfaces and needs to connect to four VLANs in the local network. How can you accomplish this task, using the fewest physical interfaces and without decreasing network performance?
A. Use a hub to connect the four VLANS with a Fast Ethernet interface on the router.
B. Add a second router to handle the VLAN traffic.
C. Add two more Fast Ethernet interfaces.
D. Implement a router-on-a-stick configuration.
Explanation/Reference:
A router on a stick allows you to use sub-interfaces to create multiple logical networks on a single physical interface.
154. Users on the 172.17.22.0 network cannot reach the server located on the 172.31.5.0 network. The network administrator connected to router Coffee via the console port, issued the show ip route command, and was able to ping the server .
on the output of the show ip route command and the topology shown in the graphic, what is the cause of the failure?
A. The network has not fully converged.
B. IP routing is not enabled.
C. A static route is configured incorrectly
D. The FastEthernet interface on Coffee is disabled.
E. The neighbor relationship table is not correctly updated.
F. The routing table on Coffee has not updated .
Explanation/Reference:
The default route or the static route was configured with incorrect next-hop ip address 172.19.22.2 The correct ip address will be 172.18.22.2 to reach server located on 172.31.5.0 network. Ip route 0.0.0.0 0.0.0.0 172.18.22.2
155. A network administrator is trying to add a new router into an established OSPF network. The networks attached to the new router do not appear in the routing tables of the other OSPF routers. Given the information in the partial configuration shown below, what configuration error is causing this problem?
Router(config)# router ospf 1
Router(config-router)# network 10.0.0.0 255.0.0.0 area 0
A. The process id is configured improperly.
B. The OSPF area is configured improperly.
C. The network wildcard mask is configured improperly.
D. The network number is configured improperly.
E. The AS is configured improperly.
F. The network subnet mask is configured improperly.
Explanation/Reference:
When configuring OSPF, the mask used for the network statement is a wildcard mask similar to an access list. In this specific example, the correct syntax would have been “network 10.0.0.0 0.0.0.255 area 0.”
156. Which Cisco Catalyst feature automatically disables the port in an operational PortFast upon receipt of a BPDU?
A. BackboneFast B. UplinkFast
C. Root Guard
D. BPDU Guard
E. BPDU Filter
Explanation/Reference:
We only enable PortFast feature on access ports (ports connected to end stations). But if someone does not know he can accidentally plug that port to another switch and a loop may occur when BPDUs are being transmitted and received on these ports. With BPDU Guard, when a PortFast receives a BPDU, it will be shut down to prevent a loop.
157. When you are troubleshooting an ACL issue on a router, which command would you use to verify which interfaces are affected by the ACL?
A. show ip access-lists
B. show access-lists
C. show interface
D. show ip interface
E. list ip interface
Explanation/Reference:
Incorrect answer:
show ip access-lists does not show interfaces affected by an ACL.
158. Host 1 is trying to communicate with Host 2. The e0 interface on Router C is down. Which of the following are true? (Choose two.)
A. Router C will use ICMP to inform Host 1 that Host 2 cannot be reached.
B. Router C will use ICMP to inform Router B that Host 2 cannot be reached.
C. Router C will use ICMP to inform Host 1, Router A, and Router B that Host 2 cannot be reached.
D. Router C will send a Destination Unreachable message type.
E. Router C will send a Router Selection message type.
F. Router C will send a Source Quench message type.
Explanation/Reference:
Host 1 is trying to communicate with Host 2. The e0 interface on Router C is down. Router C will send ICMP packets to inform Host 1 that Host 2 cannot be reached.
159. Refer to the exhibit. When running EIGRP, what is required for RouterA to exchange routing updates with RouterC?
A. AS numbers must be changed to match on all the routers
B. Loopback interfaces must be configured so a DR is elected
C. The no auto-summary command is needed on Router A and Router C
D. Router B needs to have two network statements, one for each connected network
Explanation/Reference:
This question is to examine the understanding of the interaction between EIGRP routers. The following information must be matched so as to create neighborhood. EIGRP routers to establish, must match the following information: 1. AS Number; 2. K value.
160. Cisco Catalyst switches CAT1 and CAT2 have a connection between them using ports FA0/13. An 802.1Q trunk is configured between the two switches. On CAT1, VLAN 10 is chosen as native, but on CAT2 the native VLAN is not specified. What will happen in this scenario?
A. 802.1Q giants frames could saturate the link.
B. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send untagged frames.
C. A native VLAN mismatch error message will appear.
D. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send tagged frames.
Explanation/Reference:
A “native VLAN mismatch” error will appear by CDP if there is a native VLAN mismatch on an 802.1Q link. “VLAN mismatch” can cause traffic from one vlan to leak into another vlan.
161. Refer to the exhibit. A network technician is asked to design a small network with redundancy. The exhibit represents this design, with all hosts configured in the same VLAN. What conclusions can be made about this design?
A. This design will function as intended.
B. Spanning-tree will need to be used.
C. The router will not accept the addressing scheme.
D. The connection between switches should be a trunk.
E. The router interfaces must be encapsulated with the 802.1Q protocol.
Explanation/Reference:
Each interface on a router must be in a different network. If two interfaces are in the same network, the router will not accept it and show error when the administrator assigns it.
162. Refer to the exhibit. A technician is troubleshooting host connectivity issues on the switches. The hosts in VLANs 10 and 15 on Sw11 are unable to communicate with hosts in the same VLANs on Sw12. Hosts in the Admin VLAN are able to communicate. The port-to-VLAN assignments are identical on the two switches. What could be the problem?
A. The Fa0/1 port is not operational on one of the switches.
B. The link connecting the switches has not been configured as a trunk.
C. At least one port needs to be configured in VLAN 1 for VLANs 10 and 15 to be able to communicate.
D. Port FastEthernet 0/1 needs to be configured as an access link on both switches.
E. A router is required for hosts on SW11 in VLANs 10 and 15 to communicate with hosts in the same
VLAN on Sw12.
Explanation/Reference:
In order for hosts in the same VLAN to communicate with each other over multiple switches, those switches need to be configured as trunks on their connected interfaces so that they can pass traffic from multiple VLANs.
163. Refer to the exhibit. The Bigtime router is unable to authenticate to the Littletime router. What is the cause of the problem?
A. The usernames are incorrectly configured on the two routers.
B. The passwords do not match on the two routers.
C. CHAP authentication cannot be used on a serial interface. D. The routers cannot be connected from interface S0/0 to interface S0/0.
E. With CHAP authentication, one router must authenticate to another router. The routers cannot be configured to authenticate to each other.
Explanation/Reference:
With CHAP authentication, the configured passwords must be identical on each router. Here, it is configured as little123 on one side and big123 on the other.
164. Refer to the exhibit. Given this output for SwitchC, what should the network administrator’s next action be?
A. Check the trunk encapsulation mode for SwitchC’s fa0/1 port.
B. Check the duplex mode for SwitchC’s fa0/1 port.
C. Check the duplex mode for SwitchA’s fa0/2 port.
D. Check the trunk encapsulation mode for SwitchA’s fa0/2 port.
Explanation/Reference:
Here we can see that this port is configured for full duplex, so the next step would be to check the duplex setting of the port on the other switch. A mismatched trunk encapsulation would not result in input errors and CRC errors.
165. What will happen if a private IP address is assigned to a public interface connected to an ISP?
A. Addresses in a private range will be not be routed on the Internet backbone.
B. Only the ISP router will have the capability to access the public network.
C. The NAT process will be used to translate this address to a valid IP address.
D. A conflict of IP addresses happens, because other public routers can use the same range.
Explanation/Reference:
Private RFC 1918 IP addresses are meant to be used by organizations locally within their own network only, and can not be used globally for Internet use.
166. Refer to the exhibit. An attempt to deny web access to a subnet blocks all traffic from the subnet. Which interface command immediately removes the effect of ACL 102?
A. no ip access-class 102 in
B. no ip access-class 102 out
C. no ip access-group 102 in
D. no ip access-group 102 out
E. no ip access-list 102 in
Explanation/Reference:
Now let’s find out the range of the networks on serial link:
For the network 192.168.1.62/27:
Increment: 32
Network address: 192.168.1.32
Broadcast address: 192.168.1.63 For the network 192.168.1.65/27:
Increment: 32
Network address: 192.168.1.64
Broadcast address: 192.168.1.95
-> These two IP addresses don’t belong to the same network and they can’t see each other
167. Which router IOS commands can be used to troubleshoot LAN connectivity problems? (Choose three.)
A. ping
B. tracert C. ipconfig
D. show ip route
E. winipcfg
F. show interfaces
Explanation/Reference:
Ping, show ip route, and show interfaces are all valid troubleshooting IOS commands. Tracert, ipconfig, and winipcfg are PC commands, not IOS.
168. A network administrator is troubleshooting the OSPF configuration of routers R1 and R2. The routers cannot establish an adjacency relationship on their common Ethernet link.
The graphic shows the output of the show ip ospf interface e0 command for routers R1 and R2. Based on the information in the graphic, what is the cause of this problem?
A. The OSPF area is not configured properly.
B. The priority on R1 should be set higher.
C. The cost on R1 should be set higher.
D. The hello and dead timers are not configured properly.
E. A backup designated router needs to be added to the network.
F. The OSPF process ID numbers must match.
Explanation/Reference:
In OSPF, the hello and dead intervals must match and here we can see the hello interval is set to 5 on R1 and 10 on R2. The dead interval is also set to 20 on R1 but it is 40 on R2.
169. In which circumstance are multiple copies of the same unicast frame likely to be transmitted in a switched LAN?
A. during high traffic periods
B. after broken links are re-established
C. when upper-layer protocols require high reliability
D. in an improperly implemented redundant topology
E. when a dual ring topology is in use
Explanation/Reference:
If we connect two switches via 2 or more links and do not enable STP on these switches then a loop (which creates multiple copies of the same unicast frame) will occur. It is an example of an improperly implemented redundant topology.
170. VLAN 3 is not yet configured on your switch. What happens if you set the switchport access vlan 3
command in interface configuration mode?
A. The command is rejected.
B. The port turns amber.
C. The command is accepted and the respective VLAN is added to vlan.dat.
D. The command is accepted and you must configure the VLAN manually.
Explanation/Reference:
The “switchport access vlan 3” will put that interface as belonging to VLAN 3 while also updated the VLAN database automatically to include VLAN 3.
171. A network administrator is troubleshooting an EIGRP problem on a router and needs to confirm the IP addresses of the devices with which the router has established adjacency. The retransmit interval and the queue counts for the adjacent routers also need to be checked. What command will display the required information?
A. Router# show ip eigrp adjacency
B. Router# show ip eigrp topology
C. Router# show ip eigrp interfaces
D. Router# show ip eigrp neighbors
Explanation/Reference:
Below is an example of the show ip eigrp neighbors command. The retransmit interval (Smooth Round Trip Timer – SRTT) and the queue counts (Q count, which shows the number of queued EIGRP packets) for the adjacent routers are listed:
172. Refer to the graphic. R1 is unable to establish an OSPF neighbor relationship with R3. What are possible reasons for this problem? (Choose two.)
A. All of the routers need to be configured for backbone Area 1.
B. R1 and R2 are the DR and BDR, so OSPF will not establish neighbor adjacency with R3.
C. A static route has been configured from R1 to R3 and prevents the neighbor adjacency from being
established.
D. The hello and dead interval timers are not set to the same values on R1 and R3.
E. EIGRP is also configured on these routers with a lower administrative distance.
F. R1 and R3 are configured in different areas.
Explanation/Reference:
This question is to examine the conditions for OSPF to create neighborhood. So as to make the two routers become neighbors, each router must be matched with the following items: The area ID and its types; Hello and failure time interval timer; OSPF Password (Optional);
173. Refer to the exhibit. The network shown in the diagram is experiencing connectivity problems. Which of the following will correct the problems? (Choose two.)
A. Configure the gateway on Host A as 10.1.1.1.
B. Configure the gateway on Host B as 10.1.2.254.
C. Configure the IP address of Host A as 10.1.2.2.
D. Configure the IP address of Host B as 10.1.2.2.
E. Configure the masks on both hosts to be 255.255.255.224.
F. Configure the masks on both hosts to be 255.255.255.240.
Explanation/Reference:
The switch 1 is configured with two VLANs: VLAN1 and VLAN2. The IP information of member Host A in
VLAN1 is as follows:
Address : 10.1.1.126
Mask : 255.255.255.0
Gateway : 10.1.1.254
The IP information of member Host B in VLAN2 is as follows:
Address : 10.1.1.12
Mask : 255.255.255.0
Gateway : 10.1.1.254
The configuration of sub-interface on router 2 is as follows:
Fa0/0.1 — 10.1.1.254/24 VLAN1
Fa0/0.2 — 10.1.2.254/24 VLAN2
It is obvious that the configurations of the gateways of members in VLAN2 and the associated network segments are wrong. The layer3 addressing information of Host B should be modified as follows:
Address : 10.1.2.X
Mask : 255.255.255.0
174. Refer to the exhibit. A problem with network connectivity has been observed. It is suspected that the cable connected to switch port Fa0/9 on Switch1 is disconnected. What would be an effect of this cable being disconnected?
A. Host B would not be able to access the server in VLAN9 until the cable is reconnected.
B. Communication between VLAN3 and the other VLANs would be disabled.
C. The transfer of files from Host B to the server in VLAN9 would be significantly slower.
D. For less than a minute, Host B would not be able to access the server in VLAN9. Then normal network function would resume.
Explanation/Reference:
Spanning-Tree Protocol (STP) is a Layer 2 protocol that utilizes a special-purpose algorithm to discover physical loops in a network and effect a logical loop-free topology. STP creates a loop- free tree structure consisting of leaves and branches that span the entire Layer 2 network. The actual mechanics of how bridges communicate and how the STP algorithm works will be discussed at length in the following topics. Note that the terms bridge and switch are used interchangeably when discussing STP. In addition, unless otherwise indicated, connections between switches are assumed to be trunks.
175. Refer to the exhibit. HostA cannot ping HostB. Assuming routing is properly configured, what is the cause of this problem?
A. HostA is not on the same subnet as its default gateway.
B. The address of SwitchA is a subnet address.
C. The Fa0/0 interface on RouterA is on a subnet that can’t be used.
D. The serial interfaces of the routers are not on the same subnet.
E. The Fa0/0 interface on RouterB is using a broadcast address.
Explanation/Reference:
Now let’s find out the range of the networks on serial link:
For the network 192.168.1.62/27:
Increment: 32
Network address: 192.168.1.32
Broadcast address: 192.168.1.63 For the network 192.168.1.65/27:
Increment: 32
Network address: 192.168.1.64
Broadcast address: 192.168.1.95
-> These two IP addresses don’t belong to the same network and they can’t see each other
176. Which port state is introduced by Rapid-PVST?
A. learning
B. listening
C. discarding
D. forwarding
Explanation/Reference:
PVST+ is based on IEEE802.1D Spanning Tree Protocol (STP). But PVST+ has only 3 port states (discarding, learning and forwarding) while STP has 5 port states (blocking, listening, learning, forwardingand disabled). So discarding is a new port state in PVST+.
177. Refer to the exhibit. The two connected ports on the switch are not turning orange or green. What would be the most effective steps to troubleshoot this physical layer problem? (Choose three.)
A. Ensure that the Ethernet encapsulations match on the interconnected router and switch ports.
B. Ensure that cables A and B are straight-through cables.
C. Ensure cable A is plugged into a trunk port.
D. Ensure the switch has power.
E. Reboot all of the devices.
F. Reseat all cables.
Explanation/Reference:
The ports on the switch are not up indicating it is a layer 1 (physical) problem so we should check cable type, power and how they are plugged in.
178. Refer to the exhibit. A network administrator attempts to ping Host2 from Host1 and receives the results that are shown. What is the problem?
A. The link between Host1 and Switch1 is down.
B. TCP/IP is not functioning on Host1
C. The link between Router1 and Router2 is down.
D. The default gateway on Host1 is incorrect.
E. Interface Fa0/0 on Router1 is shutdown.
F. The link between Switch1 and Router1 is down
Explanation/Reference:
Host1 tries to communicate with Host2. The message destination host unreachable from Router1 indicates that the problem occurs when the data is forwarded from Host1 to Host2. According to the topology, we can infer that The link between Router1 and Router2 is down.
179. Refer to the exhibit. Hosts in network 192.168.2.0 are unable to reach hosts in network 192.168.3.0. Based on the output from RouterA, what are two possible reasons for the failure? (Choose two.)
A. The cable that is connected to S0/0 on RouterA is faulty.
B. Interface S0/0 on RouterB is administratively down.
C. Interface S0/0 on RouterA is configured with an incorrect subnet mask.
D. The IP address that is configured on S0/0 of RouterB is not in the correct subnet
E. Interface S0/0 on RouterA is not receiving a clock signal from the CSU/DSU.
F. The encapsulation that is configured on S0/0 of RouterB does not match the encapsulation that is configured on S0/0 of RouterA
Explanation/Reference:
From the output we can see that there is a problem with the Serial 0/0 interface. It is enabled, but the line protocol is down. The could be a result of mismatched encapsulation or the interface not receiving a clock signal from the CSU/DSU.
180. Refer to the exhibit. An administrator pings the default gateway at 10.10.10.1 and sees the output as
shown. At which OSI layer is the problem?
A. data link layer
B. application layer
C. access layer
D. session layer
E. network layer
Explanation/Reference:
The command ping uses ICMP protocol, which is a network layer protocol used to propagate control message between host and router. The command ping is often used to verify the network connectivity, so it works at the network layer.
181. Which statement is correct regarding the operation of DHCP?
A. A DHCP client uses a ping to detect address conflicts.
B. A DHCP server uses a gratuitous ARP to detect DHCP clients.
C. A DHCP client uses a gratuitous ARP to detect a DHCP server.
D. If an address conflict is detected, the address is removed from the pool and an administrator must resolve the conflict.
E. If an address conflict is detected, the address is removed from the pool for an amount of time
configurable by the administrator.
F. If an address conflict is detected, the address is removed from the pool and will not be reused until the server is rebooted.
Explanation/Reference:
An address conflict occurs when two hosts use the same IP address. During address assignment, DHCP checks for conflicts using ping and gratuitous ARP. If a conflict is detected, the address is removed from the pool. The address will not be assigned until the administrator resolves the conflict.
182. Refer to the exhibit. Statements A, B, C, and D of ACL 10 have been entered in the shown order and applied to interface E0 inbound, to prevent all hosts (except those whose addresses are the first and last IP of subnet 172.21.1.128/28) from accessing the network. But as is, the ACL does not restrict anyone from the network. How can the ACL statements be re-arranged so that the system works as intended?
A. ACDB
B. BADC
C. DBAC
D. CDBA
Explanation/Reference:
Routers go line by line through an access list until a match is found and then will not look any further, even if a more specific of better match is found later on in the access list. So, it it best to begin with the most specific entries first, in this cast the two hosts in line C and D. Then, include the subnet (B) and then finally the rest of the traffic (A)
183. The output of the show frame-relay pvc command shows “PVC STATUS = INACTIVE”. What does this mean?
A. The PVC is configured correctly and is operating normally, but no data packets have been detected for
more than five minutes.
B. The PVC is configured correctly, is operating normally, and is no longer actively seeking the address of
the remote router.
C. The PVC is configured correctly, is operating normally, and is waiting for interesting traffic to trigger a
call to the remote router.
D. The PVC is configured correctly on the local switch, but there is a problem on the remote end of the PVC.
E. The PVC is not configured on the local switch.
Explanation/Reference:
The PVC STATUS displays the status of the PVC. The DCE device creates and sends the report to the
DTE devices. There are 4 statuses:
+ ACTIVE: the PVC is operational and can transmit data + INACTIVE: the connection from the local router to the switch is working, but the connection to the remote router is not available + DELETED: the PVC is not present and no LMI information is being received from the Frame Relay switch
+ STATIC: the Local Management Interface (LMI) mechanism on the interface is disabled (by using the “nokeepalive” command). This status is rarely seen so it is ignored in some books.
184. Which command is used to enable CHAP authentication, with PAP as the fallback method, on a serial
interface?
A. Router(config-if)# ppp authentication chap fallback ppp
B. Router(config-if)# ppp authentication chap pap
C. Router(config-if)# authentication ppp chap fallback ppp
D. Router(config-if)# authentication ppp chap pap
Explanation/Reference:
This command tells the router to first use CHAP and then go to PAP if CHAP isn’t available
185. Which protocol is an open standard protocol framework that is commonly used in VPNs, to provide secure
end-to-end communications?
A. RSA
B. L2TP
C. IPsec
D. PPTP
Explanation/Reference:
IPSec is a framework of open standards that provides data confidentiality, data integrity, and data authentication between participating peers at the IP layer. IPSec can be used to protect one or more data flows between IPSec peers.
186. At which layer of the OSI model does PPP perform?
A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 5
Explanation/Reference:
The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP was originally emerged as an encapsulation protocol for transporting IP traffic between two peers. It is a data link layer protocol (layer 2 in the OSI model
187. The command frame-relay map ip 10.121.16.8 102 broadcast was entered on the router. Which of the following statements is true concerning this command?
A. This command should be executed from the global configuration mode.
B. The IP address 10.121.16.8 is the local router port used to forward data. C. 102 is the remote DLCI that will receive the information
D. This command is required for all Frame Relay configurations.
E. The broadcast option allows packets, such as RIP updates, to be forwarded across the PVC.
Explanation/Reference:
Broadcast is added to the configurations of the frame relay, so the PVC supports broadcast, allowing the routing protocol updates that use the broadcast update mechanism to be forwarded across itself.
188. Which two options are valid WAN connectivity methods? (Choose two.)
A. PPP
B. WAP
C. DSL
D. L2TPv3
E. Ethernet
Explanation/Reference:
The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP was originally emerged as an encapsulation protocol for transporting IP traffic
between two peers. It is a data link layer protocol used for WAN connections. DSL is also considered a WAN connection, as it can be used to connect networks, typically when used with VPN technology.
189. Which Layer 2 protocol encapsulation type supports synchronous and asynchronous circuits and has built-in security mechanisms?
A. HDLC
B. PPP
C. X.25
D. Frame Relay
Explanation/Reference:
PPP: Provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. PPP was designed to work with several network layer protocols, including IP. PPP also has built-in security mechanisms, such as Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP).
190. Which encapsulation type is a Frame Relay encapsulation type that is supported by Cisco routers?
A. IETF
B. ANSI Annex D
C. Q9333-A Annex A
D. HDLC
Explanation/Reference:
Cisco supports two Frame Relay encapsulation types: the Cisco encapsulation and the IETF Frame Relay encapsulation, which is in conformance with RFC 1490 and RFC 2427. The former is often used to connect two Cisco routers while the latter is used to connect a Cisco router to a non-Cisco router. You can test with your Cisco router when typing the command Router(configif)# encapsulation frame-relay ? on a WAN link. Below is the output of this command (notice Cisco is the default encapsulation so it is not listed here, just press Enter to use it).
Note: Three LMI options are supported by Cisco routers are ansi, Cisco, and Q933a. They represent the ANSI Annex D, Cisco, and ITU Q933-A (Annex A) LMI types, respectively. HDLC is a WAN protocol same as Frame-Relay and PPP so it is not a Frame Relay encapsulation type
191. RouterA is unable to reach RouterB. Both routers are running IOS version 12.0. After reviewing the
command output and graphic, what is the most likely cause of the problem?
A. incorrect bandwidth configuration
B. incorrect LMI configuration
C. incorrect map statement
D. incorrect IP address
Explanation/Reference:
First we have to say this is an unclear question and it is wrong. The “frame-relay map ip” statement is correct thus none of the four answers above is correct. But we guess there is a typo in the output. Maybe the “ip address 172.16.100.2 255.255.0.0 command should be “ip address 172.16.100.1 255.255.0.0.
192. Refer to the exhibit. What is the meaning of the term dynamic as displayed in the output of the show frame-relay map command shown?
A. The Serial0/0 interface is passing traffic.
B. The DLCI 100 was dynamically allocated by the router.
C. The Serial0/0 interface acquired the IP address of 172.16.3.1 from a DHCP server. D. The DLCI 100 will be dynamically changed as required to adapt to changes in the Frame Relay cloud.
E. The mapping between DLCI 100 and the end station IP address 172.16.3.1 was learned through Inverse ARP.
Explanation/Reference:
Inverse Address Resolution Protocol (Inverse ARP) was developed to provide a mechanism for dynamic DLCI to Layer 3 address maps. Inverse ARP works much the same way Address Resolution Protocol (ARP) works on a LAN. However, with ARP, the device knows the Layer 3 IP address and needs to know the remote data link MAC address. With Inverse ARP, the router knows the Layer 2 address which is the DLCI, but needs to know the remote Layer 3 IP address. When using dynamic address mapping, Inverse ARP requests a next-hop protocol address for each active PVC. Once the requesting router receives an Inverse ARP response, it updates its DLCI-to-Layer 3 address mapping table. Dynamic address mapping is enabled by default for all protocols enabled on a physical interface. If the Frame Relay environment supports LMI autosensing and Inverse ARP, dynamic address mapping takes place automatically. Therefore, no static address mapping is required.
193. A network administrator needs to configure a serial link between the main office and a remote location. The router at the remote office is a non-Cisco router. How should the network administrator configure the serial interface of the main office router to make the connection
A. Main(config)# interface serial 0/0
Main(config-if)# ip address 172.16.1.1 255.255.255.252 Main(config-if)# no shut
B. Main(config)# interface serial 0/0
Main(config-if)# ip address 172.16.1.1 255.255.255.252
Main(config-if)# encapsulation ppp Main(config-if)# no shut
C. Main(config)# interface serial 0/0
Main(config-if)# ip address 172.16.1.1 255.255.255.252
Main(config-if)# encapsulation frame-relay
Main(config-if)# authentication chap
Main(config-if)# no shut
D. Main(config)# interface serial 0/0
Main(config-if)#ip address 172.16.1.1 255.255.255.252
Main(config-if)#encapsulation ietf
Main(config-if)# no shut
Explanation/Reference:
With serial point to point links there are two options for the encapsulation. The default, HDLC, is Cisco proprietary and works only with other Cisco routers. The other option is PPP which is standards based and
supported by all vendors.
194. What are three reasons that an organization with multiple branch offices and roaming users might
implement a Cisco VPN solution instead of point-to-point WAN links? (Choose three.)
A. reduced cost
B. better throughput
C. broadband incompatibility
D. increased security
E. scalability
F. reduced latency
Explanation/Reference:
IPsec offer a number of advantages over point to point WAN links, particularly when multiple locations are involved. These include reduced cost, increased security since all traffic is encrypted, and increased scalability as s single WAN link can be used to connect to all locations in a VPN, where as a point to point link would need to be provisioned to each location.
195. Which two statistics appear in show frame-relay map output? (Choose two.)
A. the number of BECN packets that are received by the router
B. the value of the local DLCI
C. the number of FECN packets that are received by the router
D. the status of the PVC that is configured on the router
E. the IP address of the local router
Explanation/Reference:
Sample “show frame-relay map” output:
R1#sh frame mapSerial0/0 (up): ip 10.4.4.1 dlci 401(0x191,0x6410), dynamic,broadcast,, status defined,
activeSerial0/0 (up): ip 10.4.4.3 dlci 403(0x193,0x6430), dynamic,broadcast,, status defined, activeSerial0/0
(up): ip 10.4.4.4 dlci 401(0x191,0x6410), static,CISCO, status defined, active
196. Users have been complaining that their Frame Relay connection to the corporate site is very slow. The network administrator suspects that the link is overloaded.
Based on the partial output of the Router# show frame relay pvc command shown in the graphic, which
output value indicates to the local router that traffic sent to the corporate site is experiencing congestion?
A. DLCI = 100
B. last time PVC status changed 00:25:40
C. in BECN packets 192
D. in FECN packets 147
E. in DE packets 0
Explanation/Reference:
If device A is sending data to device B across a Frame Relay infrastructure and one of the intermediate
Frame Relay switches encounters congestion, congestion being full buffers, over- subscribed port, overloaded resources, etc, it will set the BECN bit on packets being returned to the sending device and the FECN bit on the packets being sent to the receiving device.
197. Which command allows you to verify the encapsulation type (CISCO or IETF) for a Frame Relay link?
A. show frame-relay lmi
B. show frame-relay map
C. show frame-relay pvc
D. show interfaces serial
Explanation/Reference:
When connecting Cisco devices with non-Cisco devices, you must use IETF4 encapsulation on both devices. Check the encapsulation type on the Cisco device with the show frame-relay map exec command.
198. It has become necessary to configure an existing serial interface to accept a second Frame Relay virtual circuit. Which of the following procedures are required to accomplish this task? (Choose three.)
A. Remove the IP address from the physical interface.
B. Encapsulate the physical interface with multipoint PPP.
C. Create the virtual interfaces with the interface command
D. Configure each subinterface with its own IP address.
E. Disable split horizon to prevent routing loops between the subinterface networks.
F. Configure static Frame Relay map entries for each subinterface network.
Explanation/Reference:
For multiple PVC’s on a single interface, you must use subinterfaces, with each subinterface configured for each PVC. Each subinterface will then have its own IP address, and no IP address will be assigned to the main interface.
199.What occurs on a Frame Relay network when the CIR is exceeded?
A. All TCP traffic is marked discard eligible.
B. All UDP traffic is marked discard eligible and a BECN is sent.
C. All TCP traffic is marked discard eligible and a BECN is sent.
D. All traffic exceeding the CIR is marked discard eligible.
Explanation/Reference:
Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the Frame Relay switch. Frames that are sent in excess of the CIR are marked as discard eligible (DE) which means they can be dropped if the congestion occurs within the Frame Relay network. Note: In the Frame Relayframe format, there is a bit called Discard eligible (DE) bit that is used to identify frames that are first to be dropped when the CIR is exceeded.
200. Which two statements about using the CHAP authentication mechanism in a PPP link are true? (Choose two.)
A. CHAP uses a two-way handshake.
B. CHAP uses a three-way handshake.
C. CHAP authentication periodically occurs after link establishment.
D. CHAP authentication passwords are sent in plaintext.
E. CHAP authentication is performed only upon link establishment.
F. CHAP has no protection from playback attacks.
Explanation/Reference:
CHAP is an authentication scheme used by Point to Point Protocol (PPP) servers to validate the identity of remote clients. CHAP periodically verifies the identity of the client by using a three-way handshake. This happens at the time of establishing the initial link (LCP), and may happen again at any time afterwards. The verification is based on a shared secret (such as the client user’s password).
201. Refer to the exhibit. Which statement describes DLCI 17?
A. DLCI 17 describes the ISDN circuit between R2 and R3.
B. DLCI 17 describes a PVC on R2. It cannot be used on R3 or R1.
C. DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.
D. DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.
Explanation/Reference:
DLCI-Data Link Connection Identifier Bits: The DLCI serves to identify the virtual connection so that the receiving end knows which information connection a frame belongs to. Note that this DLCI has only local significance. Frame Relay is strictly a Layer 2 protocol suite.
A. Router1 will strip off the source MAC address and replace it with the MAC address 0000.0c36.6965.
B. Router1 will strip off the source IP address and replace it with the IP address 192.168.40.1.
C. Router1 will strip off the destination MAC address and replace it with the MAC address 0000.0c07.4320.
D. Router1 will strip off the destination IP address and replace it with the IP address of 192.168.40.1.
E. Router1 will forward the data packet out interface FastEthernet0/1.
F. Router1 will forward the data packet out interface FastEthernet0/2
2. Refer to the exhibit. Which three statements correctly describe Network Device A? (Choose three.)
A. With a network wide mask of 255.255.255.128, each interface does not require an IP address.
B. With a network wide mask of 255.255.255.128, each interface does require an IP address on a unique IP subnet.
C. With a network wide mask of 255.255.255.0, must be a Layer 2 device for the PCs to communicate with each other.
D. With a network wide mask of 255.255.255.0, must be a Layer 3 device for the PCs to communicate with each other.
E. With a network wide mask of 255.255.254.0, each interface does not require an IP address.
3 .Which layer in the OSI reference model is responsible for determining the availability of the receiving program and checking to see if enough resources exist for that communication?
A. transport
B. network
C. presentation
D. session
E. application
4. Refer to the exhibit. Host A pings interface S0/0 on router 3. What is the TTL value for that ping?
A. 252
B. 253
C. 254
D. 255
Explanation/Reference:
From the CCNA ICND2 Exam book: “Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it throws away the packet. This prevents packets from rotating forever.” I want to make it clear that before the router forwards a packet, the TTL is still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL.
5. Which of the following describes the roles of devices in a WAN? (Choose three.)
A. A CSU/DSU terminates a digital local loop.
B. A modem terminates a digital local loop.
C. A CSU/DSU terminates an analog local loop.
D. A modem terminates an analog local loop.
E. A router is commonly considered a DTE device.
F. A router is commonly considered a DCE device.
6. Refer to the exhibit. Refer to the exhibit. After HostA pings HostB, which entry will be in the ARP cache of HostA to support this transmission?
A. (Correct Answer: A)
B.
C.
D.
Explanation/Reference:
A Explanation:
When a host needs to reach a device on another subnet, the ARP cache entry will be that of the Ethernet address of the local router (default gateway) for the physical MAC address. The destination IP address will not change, and will be that of the remote host (HostB).
7. A network administrator is verifying the configuration of a newly installed host by establishing an FTP connection to a remote server. What is the highest layer of the protocol stack that the network administrator is using for this operation?
A. application
B. presentation
C. session
D. transport
E. internet
F. data link
Explanation/Reference:
FTP belongs to Application layer and it is also the highest layer of the OSI model. Explanation/Reference
8. A network interface port has collision detection and carrier sensing enabled on a shared twisted pair
network. From this statement, what is known about the network interface port?
A. This is a 10 Mb/s switch port.
B. This is a 100 Mb/s switch port.
C. This is an Ethernet port operating at half duplex.
D. This is an Ethernet port operating at full duplex.
E. This is a port on a network interface card in a PC.
Explanation/Reference:
Modern Ethernet networks built with switches and full-duplex connections no longer utilize CSMA/CD. CSMA/CD is only used in obsolete shared media Ethernet (which uses repeater or hub).
9. A receiving host computes the checksum on a frame and determines that the frame is damaged. The frame is then discarded. At which OSI layer did this happen?
A. session
B. transport
C. network
D. data link
E. physical
Explanation/Reference:
The Data Link layer provides the physical transmission of the data and handles error notification, network topology, and flow control. The Data Link layer formats the message into pieces, each called a data frame,and adds a customized header containing the hardware destination and source address. Protocols Data Unit (PDU) on Datalink layer is called frame. According to this question the frame is damaged and discarded which will happen at the Data Link layer.
10. Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two.)
A. The transport layer divides a data stream into segments and may add reliability and flow control information
B. The data link layer adds physical source and destination addresses and an FCS to the segment.
C. Packets are created when the network layer encapsulates a frame with source and destination host
addresses and protocol-related control information.
D. Packets are created when the network layer adds Layer 3 addresses and control information to a segment.
E. The presentation layer translates bits into voltages for transmission across the physical link.
Explanation/Reference:
The Application Layer (Layer 7) refers to communications services to applications and is the interface between the network and the application. Examples include. Telnet, HTTP, FTP, Internet browsers, NFS, SMTP gateways, SNMP, X.400 mail, and FTAM. The Presentation Layer (Layer 6) defining data formats, such as ASCII text, EBCDIC text, binary, BCD, and JPEG. Encryption also is defined as a presentation layer service. Examples include. JPEG, ASCII, EBCDIC, TIFF, GIF, PICT, encryption, MPEG, and MIDI.
The Session Layer (Layer 5) defines how to start, control, and end communication sessions. This includes the control and management of multiple bidirectional messages so that the application can be notified if only some of a series of messages are completed. This allows the presentation layer to have a seamless view of an incoming stream of data. The presentation layer can be presented with data if all flows occur in some cases. Examples include. RPC, SQL, NFS, NetBios names, AppleTalk ASP, and DECnet SCP The Transport Layer (Layer 4) defines several functions, including the choice of protocols.
The most important Layer 4 functions are error recovery and flow control. The transport layer may provide for retransmission, i.e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, or it might not, depending on the choice of protocols.
Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included. Examples include. TCP, UDP, and SPX. The Network Layer (Layer 3) defines end-to-end delivery of packets and defines logical addressing to accomplish this. It also defines how routing works and how routes are learned; and how to fragment a packet into smaller packets to accommodate media with smaller maximum transmission unit sizes.
Examples include. IP, IPX, AppleTalk DDP, and ICMP. Both IP and IPX define logical addressing, routing, the learning of routing information, and end-to-end delivery rules. The IP and IPX protocols most closely match the OSI network layer (Layer 3) and are called Layer 3 protocols because their functions most closely match OSI’s Layer 3. The Data Link Layer (Layer 2) is concerned with getting data across one particular link or medium.
The data link protocols define delivery across an individual link. These protocols are necessarily concerned with the type of media in use. Examples includE. IEEE 802.3/802.2, HDLC, Frame Relay, PPP, FDDI, ATM, and IEEE 802.5/802.2.
11. Refer to the graphic. Host A is communicating with the server. What will be the source MAC address of the
frames received by Host A from the server?
A. the MAC address of router interface e0
B. the MAC address of router interface e1
C. the MAC address of the server network interface
D. the MAC address of host A
Explanation/Reference:
Whereas switches can only examine and forward packets based on the contents of the MAC header, routers can look further into the packet to discover the network for which a packet is destined. Routers make forwarding decisions based on the packet’s network-layer header (such as an IPX header or IP header). These network-layer headers contain source and destination network addresses. Local devices address packets to the router’s MAC address in the MAC header. After receiving the packets, the router must perform the following steps:
Check the incoming packet for corruption, and remove the MAC header . The router checks the packet for MAC-layer errors. The router then strips off the MAC header and examines the network- layer header to determine what to do with the packet.
Examine the age of the packet. The router must ensure that the packet has not come too far to be forwarded. For example, IPX headers contain a hop count. By default, 15 hops is the maximum number of hops (or routers) that a packet can cross. If a packet has a hop count of 15, the router discards the packet.
IP headers contain a Time to Live (TTL) value. Unlike the IPX hop count, which increments as the packet is forwarded through each router, the IP TTL value decrements as the IP packet is forwarded through each router. If an IP packet has a TTL value of 1, the router discards the packet. A router cannot decrement the TTL value to 1 and then forward the packet. Determine the route to the destination. Routers maintain a routing table that lists available networks, the direction to the desired network (the outgoing interface number), and the distance to those networks. After determining which direction to forward the packet, the router must build a new header. (If you want to read the IP routing tables on a Windows 95/98 workstation, type
ROUTE PRINT in the DOS box.)
Build the new MAC header and forward the packet. Finally, the router builds a new MAC header for the packet. The MAC header includes the router’s MAC address and the final destination’s MAC address or the MAC address of the next router in the path.
12. Refer to the exhibit. What two results would occur if the hub were to be replaced with a switch that is configured with one Ethernet VLAN? (Choose two.)
A. The number of collision domains would remain the same.
B. The number of collision domains would decrease.
C. The number of collision domains would increase.
D. The number of broadcast domains would remain the same.
E. The number of broadcast domains would decrease.
F. The number of broadcast domains would increase.
Explanation/Reference:
Basically, a collision domain is a network segment that allows normal network traffic to flow back and forth. In the old days of hubs, this meant you had a lot of collisions, and the old CSMA/CD would be working overtime to try to get those packets re-sent every time there was a collision on the wire (since ethernet allows only one host to be transmitting at once without there being a traffic jam). With switches, you break up collision domains by switching packets bound for other collision domains. These days, since we mostly use switches to connect computers to the network, you generally have one collision domain to a PC.
Broadcast domains are exactly what they imply: they are network segments that allow broadcasts to be sent across them. Since switches and bridges allow for broadcast traffic to go unswitched, broadcasts can traverse collision domains freely. Routers, however, don’t allow broadcasts through by default, so when a broadcast hits a router (or the perimeter of a VLAN), it doesn’t get forwarded. The simple way to look at it is this way: switches break up collision domains, while routers (and VLANs) break up collision domains and broadcast domains. Also, a broadcast domain can contain multiple collision domains, but a collision domain can never have more than one broadcast domain associated with it.
Collision Domain: A group of Ethernet or Fast Ethernet devices in a CSMA/CD LAN that are connected by repeaters and compete for access on the network. Only one device in the collision domain may transmit at any one time, and the other devices in the domain listen to the network in order to avoid data collisions. A collision domain is sometimes referred to as an Ethernet segment.
Broadcast Domain: Broadcasting sends a message to everyone on the local network (subnet). An example for Broadcasting would be DHCP Request from a Client PC. The Client is asking for a IP Address, but the client does not know how to reach the DHCP Server. So the client sends a DHCP Discover packet to EVERY PC in the local subnet (Broadcast). But only the DHCP Server will answer to the Request.
How to count them?
Broadcast Domain:
No matter how many hosts or devices are connected together, if they are connected with a repeater, hub, switch or bridge, all these devices are in ONE Broadcast domain (assuming a single VLAN). A Router is used to separate Broadcast-Domains (we could also call them Subnets – or call them VLANs). So, if a router stands between all these devices, we have TWO broadcast domains.
Collision Domain:
Each connection from a single PC to a Layer 2 switch is ONE Collision domain. For example, if 5 PCs are connected with separate cables to a switch, we have 5 Collision domains. If this switch is connected to another switch or a router, we have one collision domain more. If 5 Devices are connected to a Hub, this is ONE Collision Domain. Each device that is connected to a Layer 1 device (repeater, hub) will reside in ONE single collision domain.
13. Which three statements accurately describe Layer 2 Ethernet switches? (Choose three.)
A. Spanning Tree Protocol allows switches to automatically share VLAN information.
B. Establishing VLANs increases the number of broadcast domains.
C. Switches that are configured with VLANs make forwarding decisions based on both Layer 2 and Layer 3 address information.
D. Microsegmentation decreases the number of collisions on the network.
E. In a properly functioning network with redundant switched paths, each switched segment will contain one root bridge with all its ports in the forwarding state. All other switches in that broadcast domain will have only one root port.
F. If a switch receives a frame for an unknown destination, it uses ARP to resolve the address.
Explanation/Reference:
Microsegmentation is a network design (functionality) where each workstation or device on a network gets its own dedicated segment (collision domain) to the switch. Each network device gets the full bandwidth of the segment and does not have to share the segment with other devices. Microsegmentation reduces and can even eliminate collisions because each segment is its own collision domain -> .
Note: Microsegmentation decreases the number of collisions but it increases the number of collision
domains.
14. Where does routing occur within the DoD TCP/IP reference model?
A. application
B. internet
C. network
D. transport
Explanation/Reference:
The picture below shows the comparison between TCP/IP model & OSI model. Notice that the Internet Layer of TCP/IP is equivalent to the Network Layer which is responsible for routing decision.
15. Refer to exhibit: Which destination addresses will be used by Host A to send data to Host C? (Choose two.)
A. the IP address of Switch 1
B. the MAC address of Switch 1
C. the IP address of Host C
D. the MAC address of Host C
E. the IP address of the router’s E0 interface
F. the MAC address of the router’s E0 interface
Explanation/Reference:
While transferring data through many different networks, the source and destination IP addresses are not changed. Only the source and destination MAC addresses are changed. So in this case Host A will use the IP address of Host C and the MAC address of E0 interface to send data.
When the router receives this data, it replaces the source MAC address with it own E1 interface’s MAC address and replaces the destination MAC address with Host C’s MAC address before sending to Host C .
16. For what two purposes does the Ethernet protocol use physical addresses? (Choose two.)
A. to uniquely identify devices at Layer 2
B. to allow communication with devices on a different network
C. to differentiate a Layer 2 frame from a Layer 3 packet
D. to establish a priority system to determine which device gets to transmit first
E. to allow communication between different devices on the same network
F. to allow detection of a remote device when its physical address is unknown
Explanation/Reference:
Physical addresses or MAC addresses are used to identify devices at layer 2. MAC addresses are only used to communicate on the same network. To communicate on different networkwe have to use Layer 3 addresses (IP addresses) -> B is not correct. Layer 2 frame and Layer 3 packet can be recognized via headers. Layer 3 packet also contains physical address ->
On Ethernet, each frame has the same priority to transmit by default -> All devices need a physical address to identify itself. If not, they can not communicate ->
17. Refer to the exhibit. Based on the information given, which switch will be elected root bridge and why?
A. Switch A, because it has the lowest MAC address
B. Switch A, because it is the most centrally located switch
C. Switch B, because it has the highest MAC address
D. Switch C, because it is the most centrally located switch
E. Switch C, because it has the lowest priority
F. Switch D, because it has the highest priority
Explanation/Reference:
To elect the root bridge in the LAN, first check the priority value. The switch having the lowest priority will win the election process. If Priority Value is the same then it checks the MAC Address; the switch having the lowest MAC Address will become the root bridge. In this case, switch C has the lowest MAC Address so it becomes the root bridge.
18. Refer to the exhibit. Switch-1 needs to send data to a host with a MAC address of 00b0.d056.efa4. What will Switch-1 do with this data?
A. Switch-1 will drop the data because it does not have an entry for that MAC address.
B. Switch-1 will flood the data out all of its ports except the port from which the data originated. C. Switch-1 will send an ARP request out all its ports except the port from which the data originated.
D. Switch-1 will forward the data to its default gateway.
Explanation/Reference:
This question tests the operating principles of the Layer 2 switch. Check the MAC address table of Switch1 and find that the MAC address of the host does not exist in the table. Switch1 will flood the data out all of its ports except the port from which the data originated to determine which port the host is located in. Switches work as follows: In output there is no MAC address of give host so switch floods to all ports except the source port.
19. What value is primarily used to determine which port becomes the root port on each nonroot switch in a spanning-tree topology?
A. path cost
B. lowest port MAC address
C. VTP revision number
D. highest port priority number
E. port priority number and MAC address
Explanation/Reference:
The path cost to the root bridge is the most important value to determine which port will become the root port on each non-root switch. In particular, the port with lowest cost to the root bridge will become root port (on non-root switch).
20. What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?
A. It creates a VLAN 999 interface
B. It designates VLAN 999 for untagged traffic.
C. It blocks VLAN 999 traffic from passing on the trunk.
D. It designates VLAN 999 as the default for all unknown tagged traffic.
Explanation/Reference:
Configuring the Native VLAN for Untagged Traffic A trunk port configured with 802.1Q tagging can receive both tagged and untagged traffic. By default, the switch forwards untagged traffic in the native VLAN configured for the port. The native VLAN is VLAN 1 by default.
21. Which two protocols are used by bridges and/or switches to prevent loops in a layer 2 network? (Choose two.)
A. 802.1d
B. VTP
C. 802.1q
D. STP
E. SAP
Explanation/Reference:
This question is to examine the STP protocol.
STP (802.1d) is used to prevent Layer 2 loops.
802.1q is a Frame Relay protocol which belongs to VLAN.
SAP is a concept of the OSI model.
22. Which switch would STP choose to become the root bridge in the selection process?
A. 32768: 11-22-33-44-55-66
B. 32768: 22-33-44-55-66-77
C. 32769: 11-22-33-44-55-65
D. . 32769: 22-33-44-55-66-78
23. A switch is configured with all ports assigned to vlan 2 with full duplex FastEthernet to segment existing departmental traffic. What is the effect of adding switch ports to a new VLAN on the switch?
A. More collision domains will be created.
B. IP address utilization will be more efficient.
C. More bandwidth will be required than was needed previously.
D. An additional broadcast domain will be created.
Explanation/Reference:
Each VLAN creates its own broadcast domain. Since this is a full duplex switch, each port is a separate collision domain.
24. What are three benefits of implementing VLANs? (Choose three.)
A. A higher level of network security can be reached by separating sensitive data traffic from other network traffic.
B. A more efficient use of bandwidth can be achieved allowing many physical groups to use the same
network infrastructure.
C. A more efficient use of bandwidth can be achieved allowing many logical networks to use the same network infrastructure.
D. Broadcast storms can be mitigated by increasing the number of broadcast domains, thus reducing their size.
E. Broadcast storms can be mitigated by decreasing the number of broadcast domains, thus increasing
their size.
F. VLANs make it easier for IT staff to configure new logical groups, because the VLANs all belong to the same broadcast domain.
G. Port-based VLANs increase switch-port use efficiency, thanks to 802.1Q trunks.
Explanation/Reference:
Benefits of VLANs
VLAN is a network structure which allows users to communicate while in different locations by sharing one multicast domain and a single broadcast. They provide numerous networking benefits and have become popular in the market. For instance, it helps reduce administrative costs when users are geographically
dispersed.
1. Inexpensive
The popularity of VLANs is due to the fact that changes, adds, and moves can be attained simply by making necessary configurations on the VLAN port. Time-consuming, re-addressing, and host reconfigurations is now a thing of the past, because network configuration can be made at ease when need arises.
2. Better management
A VLAN typically solve the scalability issues that exist in a large network by breaking the main domain into several VLAN groups or smaller broadcast configurations, thereby encourage better control of multicast traffic as well as broadcast domains. Improves network security High-security can be positioned in different VLAN groups to ensure that non-members cannot receive their broadcasts. On the other hand, a router is added and workgroups relocated into centralized locations.
Enhances performance A more efficient use of bandwidth can be achieved allowing many logical networks to use the same network infrastructure.
5. Segment multiple networks
VLANs are typically used to achieve multiple purposes. They are popularly used to reduce broadcast traffic. Each VLAN creates a separate, smaller broadcast domain.
6. Better administration
VLANs facilitate grouping of multiple geographical stations. When VLAN users move to another physical
location, the network does not have to be configured.
25. Which IEEE standard protocol is initiated as a result of successful DTP completion in a switch over Fast Ethernet?
A. 802.3ad
B. 802.1w
C. 802.1D
D. 802.1Q
Explanation/Reference:
Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol for negotiating trunking on a link between two devices and for negotiating the type of trunking encapsulation (802.1Q) to be used.
26. Which of the following are benefits of VLANs? (Choose three.)
A. They increase the size of collision domains.
B. They allow logical grouping of users by function.
C. They can enhance network security.
D. They increase the size of broadcast domains while decreasing the number of collision domains.
E. They increase the number of broadcast domains while decreasing the size of the broadcast domains.
F. They simplify switch administration.
Explanation/Reference:
When using VLAN the number and size of collision domains remain the same -> VLANs allow to group users by function, not by location or geography -> . VLANs help minimize the incorrect configuration of VLANs so it enhances the security of the network -> . VLAN increases the size of broadcast domains but does not decrease the number of collision domains ->
VLANs increase the number of broadcast domains while decreasing the size of the broadcast domains which increase the utilization of the links. It is also a big advantage of VLAN -> . VLANs are useful but they are more complex and need more administration ->
27. Refer to the exhibit. A technician has installed SwitchB and needs to configure it for remote access from the management workstation connected to SwitchA . Which set of commands is required to accomplish this task?
A. SwitchB(config)# interface FastEthernet 0/1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# no shutdown
B. B. SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# ip default-gateway 192.168.8.254 255.255.255.0 SwitchB
(config-if)# no shutdown
C. SwitchB(config)# ip default-gateway 192.168.8.254
SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0 SwitchB(config-
if)# no shutdown
D. SwitchB(config)# ip default-network 192.168.8.254
SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0 SwitchB(config-
if)# no shutdown
E. SwitchB(config)# ip route 192.168.8.254 255.255.255.0
SwitchB(config)# interface FastEthernet 0/1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# no shutdown
Explanation/Reference:
To remote access to SwitchB, it must have a management IP address on a VLAN on that switch. Traditionally, we often use VLAN 1 as the management VLAN (but in fact it is not secure). In the exhibit, we can recognize that the Management Workstation is in a different subnet from the SwitchB. For intersubnetwork communication to occur, you must configure at least one default gateway. This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.
28. In an Ethernet network, under what two scenarios can devices transmit? (Choose two.)
A. when they receive a special token
B. when there is a carrier
C. when they detect no other devices are sending
D. when the medium is idle
E. when the server grants access
Explanation/Reference:
Ethernet network is a shared environment so all devices have the right to access to the medium. If more than one device transmits simultaneously, the signals collide and can not reach the destination. If a device detects another device is sending, it will wait for a specified amount of time before attempting to transmit.
When there is no traffic detected, a device will transmit its message. While this transmission is occurring, the device continues to listen for traffic or collisions on the LAN. After the message is sent, the device returns to its default listening mode.
29. Which two states are the port states when RSTP has converged? (Choose two.)
A. discarding
B. listening
C. learning
D. forwarding
E. disabled
30. Which two commands can be used to verify a trunk link configuration status on a given Cisco switch interface? (Choose two.)
A. show interface trunk
B. show interface interface
C. show ip interface brief
D. show interface vlan
E. show interface switchport
31. Which of the following statements describe the network shown in the graphic? (Choose two.)
A. There are two broadcast domains in the network.
B. There are four broadcast domains in the network.
C. There are six broadcast domains in the network
D. There are four collision domains in the network.
E. There are five collision domains in the network.
F. There are seven collision domains in the network.
Explanation/Reference:
Explanation:
Only router can break up broadcast domains so in the exhibit there are 2 broadcast domains: from e0 interface to the left is a broadcast domain and from e1 interface to the right is another broadcast domain ->.
Both router and switch can break up collision domains so there is only 1 collision domain on the left of the router (because hub doesn’t break up collision domain) and there are 6 collision domains on the right of the router (1 collision domain from e1 interface to the switch + 5 collision domains for 5 PCs in Production) ->
32. Which command enables RSTP on a switch?
A. spanning-tree uplinkfast
B. spanning-tree mode rapid-pvst
C. spanning-tree backbonefast
D. spanning-tree mode mst
Explanation/Reference:
Ethernet network is a shared environment so all devices have the right to access to the medium. If more than one device transmits simultaneously, the signals collide and can not reach the destination. If a device detects another device is sending, it will wait for a specified amount of time before attempting to transmit.
When there is no traffic detected, a device will transmit its message. While this transmission is occurring, the device continues to listen for traffic or collisions on the LAN. After the message is sent, the device returns to its default listening mode.
33. Refer to the exhibit. All switch ports are assigned to the correct VLANs, but none of the hosts connected to SwitchA can communicate with hosts in the same VLAN connected to SwitchB. Based on the output shown, what is the most likely problem?
A. The access link needs to be configured in multiple VLANs.
B. The link between the switches is configured in the wrong VLAN.
C. The link between the switches needs to be configured as a trunk.
D. VTP is not configured to carry VLAN information between the switches.
E. Switch IP addresses must be configured in order for traffic to be forwarded between the switches.
Explanation/Reference:
In order to pass traffic from VLANs on different switches, the connections between the switches must be configured as trunk ports.
34. What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?
A. It creates a VLAN 999 interface.
B. It designates VLAN 999 for untagged traffic.
C. It blocks VLAN 999 traffic from passing on the trunk.
D. It designates VLAN 999 as the default for all unknown tagged traffic.
Explanation/Reference:
Configuring the Native VLAN for Untagged Traffic A trunk port configured with 802.1Q tagging can receive both tagged and untagged traffic. By default, the switch forwards untagged traffic in the native VLAN configured for the port. The native VLAN is VLAN 1 by default.
35. Refer to the exhibit. Given the output shown from this Cisco Catalyst 2950, what is the reason that interface FastEthernet 0/10 is not the root port for VLAN 2?
A. This switch has more than one interface connected to the root network segment in VLAN 2.
B. This switch is running RSTP while the elected designated switch is running 802.1d Spanning Tree.
C. This switch interface has a higher path cost to the root bridge than another in the topology.
D. This switch has a lower bridge ID for VLAN 2 than the elected designated switch.
Explanation/Reference:
Since the port is in the blocked status, we must assume that there is a shorter path to the root bridge
elsewhere.
36. Why will a switch never learn a broadcast address?
A. Broadcasts only use network layer addressing.
B. A broadcast frame is never forwarded by a switch.
C. A broadcast address will never be the source address of a frame.
D. Broadcast addresses use an incorrect format for the switching table.
E. Broadcast frames are never sent to switches.
Explanation/Reference:
Switches dynamically learn MAC addresses based on the source MAC addresses that it sees, and since a broadcast is never the source, it will never learn the broadcast address.
37. Refer to the exhibit. Why has this switch not been elected the root bridge for VLAN1?
A. It has more than one interface that is connected to the root network segment.
B. It is running RSTP while the elected root bridge is running 802.1d spanning tree
C. It has a higher MAC address than the elected root bridge.
D. It has a higher bridge ID than the elected root bridge.
Explanation/Reference:
The root bridge is determined by the lowest bridge ID, and this switch has a bridge ID priority of 32768, which is higher than the roots priority of 20481.
38. Which two link protocols are used to carry multiple VLANs over a single link? (Choose two.)
A. VTP
B. 802.1q
C. IGP
D. ISL
E. 802.3u
Explanation/Reference:
Cisco switches can use two different encapsulation types for trunks, the industry standard 802.1q or the Cisco proprietary ISL. Generally, most network engineers prefer to use 802.1q since it is standards based and will interoperate with other vendors.
39. Assuming the default switch configuration, which VLAN range can be added, modified, and removed on a Cisco switch?
A. 1 through 1001
B. 2 through 1001
C. 1 through 1002
D. 2 through 1005
Explanation/Reference:
VLAN 1 is the default VLAN on Cisco switch. It always exists and can not be added, modified or removed.
VLANs 1002-1005 are default VLANs for FDDI & Token Ring and they can’t be deleted or used for
Ethernet.
40. Which statement about VLAN operation on Cisco Catalyst switches is true?
A. When a packet is received from an 802.1Q trunk, the VLAN ID can be determined from the source
MAC address and the MAC address table.
B. Unknown unicast frames are retransmitted only to the ports that belong to the same VLAN.
C. Broadcast and multicast frames are retransmitted to ports that are configured on different VLAN.
D. Ports between switches should be configured in access mode so that VLANs can span across the
ports.
41. Refer to the topology shown in the exhibit. Which ports will be STP designated ports if all the links ar operating at the same bandwidth? (Choose three.)
A. Switch A – Fa0/0
B. Switch A – Fa0/1
C. Switch B – Fa0/0
D. Switch B – Fa0/1
E. Switch C – Fa0/0
F. Switch C – Fa0/1
Explanation/Reference:
This question is to check the spanning tree election problem. First, select the root bridge, which can be accomplished by comparing the bridge ID, the smallest will be selected. Bridge-id= bridge priority + MAC address. The three switches in the figure all have the default priority, so we should compare the MAC address, it is easy to find that SwitchB is the root bridge.
Select the root port on the non-root bridge, which can be completed through comparing root path cost. The smallest will be selected as the root port.
Next, select the Designated Port. First, compare the path cost, if the costs happen to be the same, then compare the BID, still the smallest will be selected. Each link has a DP. Based on the exhibit above, we can find DP on each link. The DP on the link between SwitchA and SwitchC is SwitchA’Fa0/1, because it has the smallest MAC address.
42. Refer to the exhibit. How should the FastEthernet0/1 ports on the 2950 model switches that are shown in the exhibit be configured to allow connectivity between all devices?
A. The ports only need to be connected by a crossover cable.
B. SwitchX(config)# interface fastethernet 0/1
SwitchX(config-if)# switchport mode trunk
C.SwitchX (config)# interface fastethernet 0/1
SwitchX (config-if)# switchport mode trunk
D.SwitchX(config)# interface fastethernet 0/1
SwitchX(config-if)# switchport mode trunk
43. Which three statements about RSTP are true? (Choose three.)
A. RSTP significantly reduces topology reconverging time after a link failure.
B. RSTP expands the STP port roles by adding the alternate and backup roles
C. RSTP port states are blocking, discarding, learning, or forwarding.
D. RSTP provides a faster transition to the forwarding state on point-to-point links than STP does.
E. RSTP also uses the STP proposal-agreement sequence.
F. RSTP uses the same timer-based process as STP on point-to-point links.
Explanation/Reference:
One big disadvantage of STP is the low convergence which is very important in switched network. To overcome this problem, in 2001, the IEEE with document 802.1w introduced an evolution of the Spanning Tree Protocol: Rapid Spanning Tree Protocol (RSTP), which significantly reduces the convergence time after a topology change occurs in the network. While STP can take 30 to 50 seconds to transit from a blocking state to a forwarding state, RSTP is typically able to respond less than 10 seconds of a physical link failure.
RSTP works by adding an alternative port and a backup port compared to STP. These ports are allowed to immediately enter the forwarding state rather than passively wait for the network to converge. RSTP bridge port roles: Root port – A forwarding port that is the closest to the root bridge in terms of path cost Designated port – A forwarding port for every LAN segment
Alternate port – A best alternate path to the root bridge. This path is different than using the root port. The alternative port moves to the forwarding state if there is a failure on the designated port for the segment.
Backup port – A backup/redundant path to a segment where another bridge port already connects. The backup port applies only when a single switch has two links to the same segment (collision domain). To have two links to the same collision domain, the switch must be attached to a hub. Disabled port – Not strictly part of STP, a network administrator can manually disable a port
44. Refer to the exhibit. A frame on VLAN 1 on switch S1 is sent to switch S2 where the frame is received on VLAN 2. What causes this behavior?
A. trunk mode mismatches
B. allowing only VLAN 2 on the destination
C. native VLAN mismatches
D. VLANs that do not correspond to a unique IP subnet
Explanation/Reference:
Untagged frames are encapsulated with the native VLAN. In this case, the native VLANs are different so although S1 will tag it as VLAN 1 it will be received by S2.
45. At which layer of the OSI model is RSTP used to prevent loops?
A. physical
B. data link
C. network
D. transport
Explanation/Reference:
RSTP and STP operate on switches and are based on the exchange of Bridge Protocol Data Units (BPDUs) between switches. One of the most important fields in BPDUs is the Bridge Priority in which the MAC address is used to elect the Root Bridge -> RSTP operates at Layer 2 ?Data Link layer -> .
46. What does a Layer 2 switch use to decide where to forward a received frame?
A. source MAC address
B. source IP address C. source switch port
C. destination IP address
D. destination port address
E. source switch port
F. destination MAC address
Explanation/Reference:
When a frame is received, the switch looks at the destination hardware address and finds the interface if it is in its MAC address table. If the address is unknown, the frame is broadcast on all interfaces except the one it was received on.
47. Refer to the exhibit. Which statement is true?
A. The Fa0/11 role confirms that SwitchA is the root bridge for VLAN 20.
B. VLAN 20 is running the Per VLAN Spanning Tree Protocol.
C. The MAC address of the root bridge is 0017.596d.1580.
D. SwitchA is not the root bridge, because not all of the interface roles are designated.
Explanation/Reference:
Only non-root bridge can have root port. Fa0/11 is the root port so we can confirm this switch is not the root bridge ->
From the output we learn this switch is running Rapid STP, not PVST -> 0017.596d.1580 is the MAC address of this switch, not of the root bridge. The MAC address of the root bridge is 0017.596d.2a00 -> All of the interface roles of the root bridge are designated. SwitchA has one Root port and 1 Alternative port so it is not the root bridge.
48. Which two benefits are provided by creating VLANs? (Choose two.)
A. added security
B. dedicated bandwidth
C. provides segmentation
D. allows switches to route traffic between subinterfaces
E. contains collisions
Explanation/Reference:
A VLAN is a switched network that is logically segmented on an organizational basis, by functions, project teams, or applications rather than on a physical or geographical basis. Security: VLANs also improve security by isolating groups. High-security users can be grouped into a VLAN, possible on the same physical segment, and no users outside that VLAN can communicate with them LAN Segmentation VLANs allow logical network topologies to overlay the physical switched infrastructure such that any arbitrary collection of LAN ports can be combined into an autonomous user group or community of interest. The technology logically segments the network into separate Layer 2 broadcast domains whereby packets
are switched between ports designated to be within the same VLAN. By containing traffic originating on a particular LAN only to other LANs in the same VLAN, switched virtual networks avoid wasting bandwidth.
49. Which command can be used from a PC to verify the connectivity between hosts that connect through a switch in the same LAN?
A. pingaddress
B. tracert address
C. traceroute address
D. arpaddress
Explanation/Reference:
ICMP pings are used to verify connectivity between two IP hosts. Traceroute is used to verify the router hop path traffic will take but in this case since the hosts are in the same LAN there will be no router hops involved.
50. Based on the network shown in the graphic. Which option contains both the potential networking problem and the protocol or setting that should be used to prevent the problem?
A. routing loops, hold down timers
B. switching loops, split horizon
C. routing loops, split horizon
D. switching loops, VTP
E. routing loops, STP
F. switching loops, STP
Explanation/Reference:
The Spanning-Tree Protocol (STP) prevents loops from being formed when switches or bridges are interconnected via multiple paths. Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices.
51. Refer to the exhibit. Which two statements are true about interVLAN routing in the topology that is shown in the exhibit? (Choose two.)
A. Host E and host F use the same IP gateway address.
B. Router1 and Switch2 should be connected via a crossover cable.
C. Router1 will not play a role in communications between host A and host D
D. The FastEthernet 0/0 interface on Router1 must be configured with subinterfaces.
E. Router1 needs more LAN interfaces to accommodate the VLANs that are shown in the exhibit.
F. The FastEthernet 0/0 interface on Router1 and the FastEthernet 0/1 interface on Switch2 trunk ports must be configured using the same encapsulation type
52. Which two of these are characteristics of the 802.1Q protocol? (Choose two.)
A. It is used exclusively for tagging VLAN frames and does not address network reconvergence
B. It modifies the 802.3 frame header, and thus requires that the FCS be recomputed.
C. It is a Layer 2 messaging protocol which maintains VLAN configurations across networks.
D. It includes an 8-bit field which specifies the priority of a frame.
E. It is a trunking protocol capable of carrying untagged frames.
Explanation/Reference:
802.1Q protocol, or Virtual Bridged Local Area Networks protocol, mainly stipulates the realization of the VLAN. 802.1Q is a standardized relay method that inserts 4 bytes field into the original Ethernet frame and re-calculate the FCS. 802.1Q frame relay supports two types of frame: marked and non-marked. Non- marked frame carries no VLAN identification information.
53. Refer to the exhibit. Each of these four switches has been configured with a hostname, as well as being configured to run RSTP. No other configuration changes have been made. Which three of these show the correct RSTP port roles for the indicated switches and interfaces? (Choose three.)
A. SwitchA, Fa0/2, designated
B. SwitchA, Fa0/1, root
C. SwitchB, Gi0/2, root
D. SwitchB, Gi0/1, designated
E. SwitchC, Fa0/2, root
F. SwitchD, Gi0/2, root
Explanation/Reference:
The question says “no other configuration changes have been made” so we can understand these switches have the same bridge priority. Switch C has lowest MAC address so it will become root bridge and 2 of its ports (Fa0/1 & Fa0/2) will be designated ports. Because SwitchC is the root bridge so the 2 ports nearest SwitchC on SwitchA (Fa0/1) and SwitchD (Gi0/2) will be root ports..
Now we come to the most difficult part of this question: SwitchB must have a root port so which port will it choose? To answer this question we need to know about STP cost and port cost. In general, “cost” is calculated based on bandwidth of the link. The higher the bandwidth on a link, the lower the value of its cost. Below are the cost values you should memorize:
SwitchB will choose the interface with lower cost to the root bridge as the root port so we must calculate the cost on interface Gi0/1 & Gi0/2 of SwitchB to the root bridge. This can be calculated from the “cost to the root bridge” of each switch because a switch always advertises its cost to the root bridge in its BPDU. The receiving switch will add its local port cost value to the cost in the BPDU. One more thing to notice is that a root bridge always advertises the cost to the root bridge (itself) with an initial value of 0. Now let’s have a look at the topology again
SwitchC advertises its cost to the root bridge with a value of 0. Switch D adds 4 (the cost value of 1Gbps link) and advertises this value (4) to SwitchB. SwitchB adds another 4 and learns that it can reach SwitchC via Gi0/1 port with a total cost of 8. The same process happens for SwitchA and SwitchB learns that it canreach SwitchC via Gi0/2 with a total cost of 23 -> Switch B chooses Gi0/1 as its root port ->
Now our last task is to identify the port roles of the ports between SwitchA & SwitchB. It is rather easy as the MAC address of SwitchA is lower than that of SwitchB so Fa0/2 of SwitchA will be designated port while Gi0/2 of SwitchB will be alternative port.
Below summaries all the port roles of these switches:
+ DP: Designated Port (forwarding state)
+ RP: Root Port (forwarding state)
54. What is one benefit of PVST+?
A. PVST+ supports Layer 3 load balancing without loops.
B. PVST+ reduces the CPU cycles for all the switches in the network.
C. PVST+ allows the root switch location to be optimized per VLAN.
D. PVST+ automatically selects the root bridge location, to provide optimized bandwidth usage.
Explanation/Reference:
The PVST+ provides Layer 2 load-balancing for the VLAN on which it runs. You can create different logical topologies by using the VLANs on your network to ensure that all of your links are used but that no one link is oversubscribed. Each instance of PVST+ on a VLAN has a single root switch. This root switch propagates the spanning-tree information associated with that VLAN to all other switches in the network.
Because each switch has the same information about the network, this process ensures that the network topology is maintained and optimized per VLAN. http://www.cisco.com/en/US/docs/switches/lan/ catalyst3750x_3560x/software/release/12.2_55_s e/configuration/guide/swstp.html
55. Refer to the exhibit. The network administrator normally establishes a Telnet session with the switch from host A . However, host A is unavailable. The administrator’s attempt to telnet to the switch from host B fails, but pings to the other two hosts are successful. What is the issue?
A. Host B and the switch need to be in the same subnet.
B. The switch interface connected to the router is down.
C. Host B needs to be assigned an IP address in VLAN 1.
D. The switch needs an appropriate default gateway assigned.
E. The switch interfaces need the appropriate IP addresses assigned.
Explanation/Reference:
Ping was successful form host B to other hosts because of intervlan routing configured on router. But to manage switch via telnet the VLAN32 on the switch needs to be configured interface vlan32 along with ip address and its appropriate default-gateway address. Since VLAN1 interface is already configure on switch Host A was able to telnet switch.
56. Which are valid modes for a switch port used as a VLAN trunk? (Choose three.)
A. transparent
B. auto
C. on
D. desirable
E. blocking
F. forwarding
57.Refer to the exhibit. Which switch provides the spanning-tree designated port role for the network segment that services the printers?
A. SW1
B. SW2
C. SW3
D. SW4
Explanation/Reference:
Printers are connected by hubs. Decide the switch that provides the spanning-tree designated port role between Switch3 and Switch4. They have the same priority 32768. Compare their MAC addresses. Switch3 with a smaller MAC address will provide a designated port for printers.
58. Refer to Exhibit. How many broadcast domains are shown in the graphic assuming only the default VLAN is
configured on the switches?
A. 1
B. 2
C. 6
D. 11
Explanation/Reference:
Only router can break up broadcast domains but in this exhibit no router is used so there is only 1 broadcast domain.
For your information, there are 7 collision domains in this exhibit (6 collision domains between hubs & switches + 1 collision between the two switches).
59. Which three of these statements regarding 802.1Q trunking are correct? (Choose three.)
A. 802.1Q native VLAN frames are untagged by default.
B. 802.1Q trunking ports can also be secure ports.
C. 802.1Q trunks can use 10 Mb/s Ethernet interfaces.
D. 802.1Q trunks require full-duplex, point-to-point connectivity.
E. 802.1Q trunks should have native VLANs that are the same at both ends.
Explanation/Reference:
By default, 802.1Q trunk defined Native VLAN in order to forward unmarked frame. Switches can forward Layer 2 frame from Native VLAN on unmarked trunks port. Receiver switches will transmit all unmarked packets to Native VLAN. Native VLAN is the default VLAN configuration of port. Note for the 802.1Q trunk ports between two devices, the same Native VLAN configuration is required on both sides of the link. If the Native VLAN in 802.1Q trunk ports on same trunk link is properly configured, it could lead to layer 2 loops. The 802.1Q trunk link transmits VLAN information through Ethernet.
60. Refer to the exhibit. The output that is shown is generated at a switch. Which three statements are true? (Choose three.)
A. All ports will be in a state of discarding, learning, or forwarding.
B. Thirty VLANs have been configured on this switch.
C. The bridge priority is lower than the default value for spanning tree.
D. All interfaces that are shown are on shared media.
E. All designated ports are in a forwarding state. F. This switch must be the root bridge for all VLANs on this switch.
Explanation/Reference:
From the output, we see that all ports are in Designated role (forwarding state). The command “show spanning-tree vlan 30 only shows us information about VLAN 30. We don’t know how many VLAN exists in
this switch ->
The bridge priority of this switch is 24606 which is lower than the default value bridge priority 32768 -> . All three interfaces on this switch have the connection type “p2p”, which means Point-to-point environment ?not a shared media >;
The only thing we can specify is this switch is the root bridge for VLAN 3o but we can not guarantee it is also the root bridge for other VLANs ->
61. Refer to the exhibit. At the end of an RSTP election process, which access layer switch port will assume the
discarding role?
A. Switch3, port fa0/1
B. Switch3, port fa0/12
C. Switch4, port fa0/11
D. Switch4, port fa0/2
E. Switch3, port Gi0/1
F. Switch3, port Gi0/2
Explanation/Reference:
In this question, we only care about the Access Layer switches (Switch3 & 4). Switch 3 has a lower bridge ID than Switch 4 (because the MAC of Switch3 is smaller than that of Switch4) so both ports of Switch3 will be in forwarding state. The alternative port will surely belong to Switch4. Switch4 will need to block one of its ports to avoid a bridging loop between the two switches. But how does Switch4 select its blocked port?
Well, the answer is based on the BPDUs it receives from Switch3. A BPDU is superior than another if it has:
A lower Root Bridge ID
A lower path cost to the Root
A lower Sending Bridge ID
A lower Sending Port ID
These four parameters are examined in order. In this specific case, all the BPDUs sent by Switch3 have the same Root Bridge ID, the same path cost to the Root and the same Sending Bridge ID.The only parameter left to select the best one is the Sending Port ID (Port ID = port priority + port index). In this case the port priorities are equal because they use the default value, so Switch4 will compare port index values, which are unique to each port on the switch, and because Fa0/12 is inferior to Fa0/1, Switch4 will select the port connected with Fa0/1 (of Switch3) as its root port and block the other port -> Port fa0/11 of Switch4 will be blocked (discarding role).
62. Which term describes a spanning-tree network that has all switch ports in either the blocking or fowarding
state?
A. converged
B. redundant
C. provisioned
D. spanned
Explanation/Reference:
Spanning Tree Protocol convergence (Layer 2 convergence) happens when bridges and switches have transitioned to either the forwarding or blocking state. When layer 2 is converged, root bridge is elected and all port roles (Root, Designated and Non-Designated) in all switches are selected.
63. What are the possible trunking modes for a switch port? (Choose three.)
A. transparent
B. auto
C. on
D. desirable
E. client
F. forwarding
64. Which two of these statements regarding RSTP are correct? (Choose two.)
A. RSTP cannot operate with PVST+.
B. RSTP defines new port roles.
C. RSTP defines no new port states.
D. RSTP is a proprietary implementation of IEEE 802.1D STP.
E. RSTP is compatible with the original IEEE 802.1D STP.
Explanation/Reference:
When network topology changes, rapid spanning tree protocol (IEEE802.1W, referred to as RSTP) will speed up significantly the speed to re-calculate spanning tree. RSTP not only defines the role of other ports: alternative port and backup port, but also defines status of 3 ports: discarding status, learning status,forwarding status. RSTP is 802.1D standard evolution, not revolution. It retains most of the parameters, and makes no changes.
65. Refer to the exhibit. Which two statements are true of the interfaces on Switch1? (Choose two.)
A. Multiple devices are connected directly to FastEthernet0/1.
B. A hub is connected directly to FastEthernet0/5.
C. FastEthernet0/1 is connected to a host with multiple network interface cards.
D. FastEthernet0/5 has statically assigned MAC addresses.
E. FastEthernet0/1 is configured as a trunk link.
F. Interface FastEthernet0/2 has been disabled.
Explanation/Reference:
Carefully observe the information given after command show. Fa0/1 is connected to Switch2, seven MAC addresses correspond to Fa0/1, and these MAC are in different VLAN. From this we know that Fa0/1 is the trunk interface.
From the information given by show cdp neighbors we find that there is no Fa0/5 in CDP neighbor. However, F0/5 corresponds to two MAC addresses in the same VLAN. Thus we know that Fa0/5 is connected to a Hub. Based on the output shown, there are multiple MAC addresses from different VLANs attached to the FastEthernet 0/1 interface. Only trunks are able to pass information from devices in multiple VLANs.
66. Three switches are connected to one another via trunk ports. Assuming the default switch configuration, which switch is elected as the root bridge for the spanning-tree instance of VLAN 1?
A. the switch with the highest MAC address
B. the switch with the lowest MAC address
C. the switch with the highest IP address
D. the switch with the lowest IP address
Explanation/Reference:
Each switch in your network will have a Bridge ID Priority value, more commonly referred to as a BID. This BID is a combination of a default priority value and the switch’s MAC address, with the priority value listed first. The lowest BID will win the election process.
For example, if a Cisco switch has the default priority value of 32,768 and a MAC address of 11- 22-33-44- 55-66, the BID would be 32768:11-22-33-44-55-66. Therefore, if the switch priority is left at the default, the MAC address is the deciding factor in the root bridge election.
67. What are three advantages of VLANs? (Choose three.)
A. VLANs establish broadcast domains in switched networks.
B. VLANs utilize packet filtering to enhance network security.
C. VLANs provide a method of conserving IP addresses in large networks.
D. VLANs provide a low-latency internetworking alternative to routed networks.
E. VLANs allow access to network services based on department, not physical location.
F. VLANs can greatly simplify adding, moving, or changing hosts on the network.
Explanation/Reference:
VLAN technology is often used in practice, because it can better control layer2 broadcast to improve network security. This makes network more flexible and scalable. Packet filtering is a function of firewall
instead of VLAN.
68. Which two benefits are provided by using a hierarchical addressing network addressing scheme? (Choose two.)
A. reduces routing table entries
B. auto-negotiation of media rates
C. efficient utilization of MAC addresses
D. dedicated communications between devices
E. ease of management and troubleshooting
Explanation/Reference:
Here are some of the benefits of hierarchical addressing: Reference: http://www.ciscopress.com/articles/article.asp p=174107
69. What is the alternative notation for the IPv6 address B514:82C3:0000:0000:0029:EC7A:0000:EC72?
A. B514 : 82C3 : 0029 : EC7A : EC72
B. B514 : 82C3 :: 0029 : EC7A : EC72
C. B514 : 82C3 : 0029 :: EC7A : 0000 : EC72
D. B514 : 82C3 :: 0029 : EC7A : 0 : EC72
Explanation/Reference:
There are two ways that an IPv6 address can be additionally compressed: compressing leading zeros and substituting a group of consecutive zeros with a single double colon (::). Both of these can be used in any number of combinations to notate the same address. It is important to note that the double colon (::) can only be used once within a single IPv6 address notation. So, the extra 0’s can only be compressed once.
70. Refer to the diagram. All hosts have connectivity with one another. Which statements describe the addressing scheme that is in use in the network? (Choose three.)
A. The subnet mask in use is 255.255.255.192.
B. The subnet mask in use is 255.255.255.128.
C. The IP address 172.16.1.25 can be assigned to hosts in VLAN1
D. The IP address 172.16.1.205 can be assigned to hosts in VLAN1
E. The LAN interface of the router is configured with one IP address.
F. The LAN interface of the router is configured with multiple IP addresses.
Explanation/Reference:
The subnet mask in use is 255.255.255.128: This is subnet mask will support up to 126 hosts, which is
needed. The IP address 172.16.1.25 can be assigned to hosts in VLAN1: The usable host range in this subnet is
172.16.1.1-172.16.1.126 The LAN interface of the router is configured with multiple IP addresses: The router will need 2
subinterfaces for the single physical interface, one with an IP address that belongs in each VLAN.
71. Which two statements describe characteristics of IPv6 unicast addressing? (Choose two.)
A. Global addresses start with 2000::/3.
B. Link-local addresses start with FE00:/12.
C. Link-local addresses start with FF00::/10.
D. There is only one loopback address and it is ::1.
E. If a global address is assigned to an interface, then that is the only allowable address for the interface.
Explanation/Reference:
Below is the list of common kinds of IPv6 addresses:
72. The network administrator has been asked to give reasons for moving from IPv4 to IPv6. What are two valid reasons for adopting IPv6 over IPv4? (Choose two.)
A. no broadcast
B. change of source address in the IPv6 header
C. change of destination address in the IPv6 header
D. Telnet access does not require a password
E. autoconfiguration
F. NAT
Explanation/Reference:
IPv6 does not use broadcasts, and autoconfiguration is a feature of IPV6 that allows for hosts to automatically obtain an IPv6 address.
73. An administrator must assign static IP addresses to the servers in a network. For network 192.168.20.24/29, the router is assigned the first usable host address while the sales server is given the last usable host address. Which of the following should be entered into the IP properties box for the sales server?
A. IP address: 192.168.20.14 Subnet Mask: 255.255.255.248
Default Gateway: 192.168.20.9
B. IP address: 192.168.20.254 Subnet Mask: 255.255.255.0 Default Gateway:
192.168.20.1
C. IP address: 192.168.20.30 Subnet Mask: 255.255.255.248
Default Gateway: 192.168.20.25
D. IP address: 192.168.20.30
Subnet Mask: 255.255.255.240
Default Gateway: 192.168.20.17
E. IP address: 192.168.20.30 Subnet Mask: 255.255.255.240
Default Gateway: 192.168.20.25
Explanation/Reference:
For the 192.168.20.24/29 network, the usable hosts are 192.168.24.25 (router) ?192.168.24.30 (used for the sales server).
74. Which subnet mask would be appropriate for a network address range to be subnetted for up to eight LANs, with each LAN containing 5 to 26 hosts?
A. 0.0.0.240
B. 255.255.255.252
C. 255.255.255.0
D. 255.255.255.224
E. 255.255.255.240
Explanation/Reference:
For a class C network, a mask of 255.255.255.224 will allow for up to 8 networks with 32 IP addresses each (30 usable).
75. How many bits are contained in each field of an IPv6 address?
A. 24
B. 4
C. 8
D. 16
Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
76. What are three approaches that are used when migrating from an IPv4 addressing scheme to an IPv6 scheme. (Choose three.)
A. enable dual-stack routing
B. configure IPv6 directly
C. configure IPv4 tunnels between IPv6 islands
D. use proxying and translation to translate IPv6 packets into IPv4 packets
E. statically map IPv4 addresses to IPv6 addresses
F. use DHCPv6 to map IPv4 addresses to IPv6 addresses
Explanation/Reference:
Several methods are used terms of migration including tunneling, translators, and dual stack. Tunnels are used to carry one protocol inside another, while translators simply translate IPv6 packets into IPv4 packets. Dual stack uses a combination of both native IPv4 and IPv6. With dual stack, devices are able to run IPv4 and IPv6 together and if IPv6 communication is possible that is the preferred protocol. Hosts can simultaneously reach IPv4 and IPv6 content.
77. Refer to the exhibit. In this VLSM addressing scheme, what summary address would be sent from router A?
A. 172.16.0.0 /16
B. 172.16.0.0 /20
C. 172.16.0.0 /24
D. 172.32.0.0 /16
E. 172.32.0.0 /17
F. 172.64.0.0 /16
Explanation/Reference:
Router A receives 3 subnets: 172.16.64.0/18, 172.16.32.0/24 and 172.16.128.0/18. All these 3 subnets have the same form of 172.16.x.x so our summarized subnet must be also in that form -> Only A, B or . The smallest subnet mask of these 3 subnets is /18 so our summarized subnet must also have its subnet mask equal or smaller than /18. -> Only answer A has these 2 conditions -> .
78. How is an EUI-64 format interface ID created from a 48-bit MAC address?
A. by appending 0xFF to the MAC address
B. by prefixing the MAC address with 0xFFEE
C. by prefixing the MAC address with 0xFF and appending 0xFF to it
D. by inserting 0xFFFE between the upper three bytes and the lower three bytes of the MAC address E. by prefixing the MAC address with 0xF and inserting 0xF after each of its first three bytes
Explanation/Reference:
The modified EUI-64 format interface identifier is derived from the 48-bit link-layer (MAC) address by inserting the hexadecimal number FFFE between the upper three bytes (OUI field) and the lower three bytes (serial number) of the link layer address.
79. Refer to the exhibit. What is the most efficient summarization that R1 can use to advertise its networks to R2?
A. 172.1.0.0/22
B. 172.1.0.0/21
C. 172.1.4.0/22
D. 172.1.4.0/24
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24
E. 172.1.4.0/25
172.1.4.128/25
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24
Explanation/Reference:
The 172.1.4.0/22 subnet encompasses all routes from the IP range 172.1.4.0 ?172.1.7.255.
80. Which option is a valid IPv6 address?
A. 2001:0000:130F::099a::12a
B. 2002:7654:A1AD:61:81AF:CCC1
C. FEC0:ABCD:WXYZ:0067::2A4
D. 2004:1:25A4:886F::1
Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.
81. Which three are characteristics of an IPv6 anycast address? (Choose three.)
A. one-to-many communication model
B. one-to-nearest communication model
C. any-to-many communication model
D. a unique IPv6 address for each device in the group E. the same address for multiple devices in the group
F. delivery of packets to the group interface that is closest to the sending device
Explanation/Reference:
A new address type made specifically for IPv6 is called the Anycast Address. These IPv6 addresses are global addresses, these addresses can be assigned to more than one interface unlike an IPv6 unicast address. Anycast is designed to send a packet to the nearest interface that is apart of that anycast group.
The sender creates a packet and forwards the packet to the anycast address as the destination address which goes to the nearest router. The nearest router or interface is found by using the metric of a routing protocol currently running on the network. However in a LAN setting the nearest interface is found depending on the order the neighbors were learned. The anycast packet in a LAN setting forwards the packet to the neighbor it learned about first.
82. A national retail chain needs to design an IP addressing scheme to support a nationwide network. The company needs a minimum of 300 sub-networks and a maximum of 50 host addresses per subnet. Working with only one Class B address, which of the following subnet masks will support an appropriate addressing scheme? (Choose two.)
A. 255.255.255.0
B. 255.255.255.128
C. 255.255.252.0
D. 255.255.255.224
E. 255.255.255.192
F. 255.255.248.0
Explanation/Reference:
Subnetting is used to break the network into smaller more efficient subnets to prevent excessive rates of Ethernet packet collision in a large network. Such subnets can be arranged hierarchically, with the organization’s network address space (see also Autonomous System) partitioned into a tree-like structure. Routers are used to manage traffic and constitute borders between subnets. A routing prefix is the sequence of leading bits of an IP address that precede the portion of the address used as host identifier. In
IPv4 networks, the routing prefix is often expressed as a “subnet mask”, which is a bit mask covering the number of bits used in the prefix. An IPv4 subnet mask is frequently expressed in quad-dotted decimal representation, e.g., 255.255.255.0 is the subnet mask for the 192.168.1.0 network with a 24-bit routing prefix (192.168.1.0/24).
83. Refer to the exhibit. A network administrator is adding two new hosts to Switch A . Which three values could be used for the configuration of these hosts? (Choose three.)
A. host A IP address: 192.168.1.79
B. host A IP address: 192.168.1.64
C. host A default gateway: 192.168.1.78
D. host B IP address: 192.168.1.128
E. host B default gateway: 192.168.1.129
F. host B IP address: 192.168.1.190
84. Which IPv6 address is the all-router multicast group?
A. FF02::1
B. FF02::2
C. FF02::3
D. FF02::4
Explanation/Reference:
Well-known IPv6 multicast addresses:
Address Description
ff02::1
All nodes on the local network segment ff02::2
All routers on the local network segment
85. Refer to the exhibit. Which address range efficiently summarizes the routing table of the addresses for router Main?
A. 172.16.0.0/21
B. 172.16.0.0/20
C. 172.16.0.0/16
D. 172.16.0.0/18
Explanation/Reference:
The 172.16.0.0./20 network is the best option as it includes all networks from 172.16.0.0 – 172.16.16.0 and does it more efficiently than the /16 and /18 subnets. The /21 subnet will not include all the other subnets in this one single summarized address.
86. Which IPv6 address is valid
A. 2001:0db8:0000:130F:0000:0000:08GC:140B
B. 2001:0db8:0:130H::87C:140B
C. 2031::130F::9C0:876A:130B
D. 2031:0:130F::9C0:876A:130B
Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.
87. Which command can you use to manually assign a static IPv6 address to a router interface?
A. ipv6 autoconfig 2001:db8:2222:7272::72/64
B. ipv6 address 2001:db8:2222:7272::72/64
C. ipv6 address PREFIX_1 ::1/64
D. ipv6 autoconfig
ExplanationExplanation/Reference:
To assign an IPv6 address to an interface, use the “ipv6 address” command and specify the IP address you
wish to use.
88. Which of these represents an IPv6 link-local address?
A. FE80::380e:611a:e14f:3d69
B. FE81::280f:512b:e14f:3d69
C. FEFE:0345:5f1b::e14d:3d69
D. FE08::280e:611:a:f14f:3d69
Explanation/Reference:
In the Internet Protocol Version 6 (IPv6), the address block fe80::/10 has been reserved for link- local unicast addressing. The actual link local addresses are assigned with the prefix fe80::/64. They may be assigned by automatic (stateless) or stateful (e.g. manual) mechanisms.
89. The network administrator is asked to configure 113 point-to-point links. Which IP addressing scheme defines the address range and subnet mask that meet the requirement and waste the fewest subnet and host addresses?
A. 10.10.0.0/16 subnetted with mask 255.255.255.252
B. 10.10.0.0/18 subnetted with mask 255.255.255.252
C. 10.10.1.0/24 subnetted with mask 255.255.255.252
D. 10.10.0.0/23 subnetted with mask 255.255.255.252
E. 10.10.1.0/25 subnetted with mask 255.255.255.252
Explanation/Reference:
We need 113 point-to-point links which equal to 113 sub-networks < 128 so we need to borrow 7 bits (because 2^7 = 128).
The network used for point-to-point connection should be /30. So our initial network should be 30 ?7 = 23. So 10.10.0.0/23 is the correct answer.
You can understand it more clearly when writing it in binary form:
/23 = 1111 1111.1111 1110.0000 0000
/30 = 1111 1111.1111 1111.1111 1100 (borrow 7 bits)
90. A Cisco router is booting and has just completed the POST process. It is now ready to find and load an IOS image. What function does the router perform next?
A. It checks the configuration register.
B. It attempts to boot from a TFTP server.
C. It loads the first image file in flash memory.
D. It inspects the configuration file in NVRAM for boot instructions.
Explanation/Reference:
Default (normal) Boot SequencePower on Router – Router does POST – Bootstrap starts IOS load – Check configuration registerto see what mode the router should boot up in (usually 0x2102 to read startup-config in NVRAM / or 0x2142 to start in “setup-mode”) – check the startup-config file in NVRAM for boot-system commands – load IOS from Flash.
91.Refer to the exhibit. What is the meaning of the output MTU 1500 bytes?
A. The maximum number of bytes that can traverse this interface per second is 1500.
B. The minimum segment size that can traverse this interface is 1500 bytes.
C. The maximum segment size that can traverse this interface is 1500 bytes.
D. The minimum packet size that can traverse this interface is 1500 bytes.
E. The maximum packet size that can traverse this interface is 1500 bytes.
F. The maximum frame size that can traverse this interface is 1500 bytes.
Explanation/Reference:
The Maximum Transmission Unit (MTU) defines the maximum Layer 3 packet (in bytes) that the layer can pass onwards.
92. On a corporate network, hosts on the same VLAN can communicate with each other, but they are unable to communicate with hosts on different VLANs. What is needed to allow communication between the VLANs?
A. a router with subinterfaces configured on the physical interface that is connected to the switch
B. router with an IP address on the physical interface connected to the switch
C. a switch with an access link that is configured between the switches
D. a switch with a trunk link that is configured between the switches
Explanation/Reference:
Different VLANs can’t communicate with each other , they can communicate with the help of Layer3 router. Hence , it is needed to connect a router to a switch , then make the sub-interface on the router to connect to the switch, establishing Trunking links to achieve communications of devices which belong to different VLANs.
When using VLANs in networks that have multiple interconnected switches, you need to use VLAN trunking between the switches. With VLAN trunking, the switches tag each frame sent between switches so that the receiving switch knows to what VLAN the frame belongs. End user devices connect to switch ports that provide simple connectivity to a single VLAN each. The attached devices are unaware of any VLAN structure.
By default, only hosts that are members of the same VLAN can communicate. To change this and allow inter-VLAN communication, you need a router or a layer 3 switch. Here is the example of configuring the router for inter-vlan communication RouterA(config)#int f0/0.1
RouterA(config-subif)#encapsulation ? dot1Q IEEE 802.1Q Virtual LAN
RouterA(config-subif)#encapsulation dot1Q or isl VLAN ID RouterA(config-subif)# ip address x.x.x.x y.y.y.y
93. Which command displays CPU utilization?
A. show protocols
B. show process
C. show system
D. show version
Explanation/Reference:
The “show process” (in fact, the full command is “show processes”) command gives us lots of information about each process but in fact it is not easy to read. Below shows the output of this command (some next pages are omitted)
A more friendly way to check the CPU utilization is the command “show processes cpu history”, in which the total
CPU usage on the router over a period of time: one minute, one hour, and 72 hours are clearly shown
+ The Y- axis of the graph is the CPU utilization.+ The X-axis of the graph is the increment within the period displayed in the graph. For example, from the last graph (last 72 hours) we learn that the highest CPU utilization within 72 hours is 37% about six hours ago.
94. What two things will a router do when running a distance vector routing protocol? (Choose two.)
A. Send periodic updates regardless of topology changes.
B. Send entire routing table to all routers in the routing domain.
C. Use the shortest-path algorithm to the determine best path.
D. Update the routing table based on updates from their neighbors.
E. Maintain the topology of the entire network in its database.
Explanation/Reference:
Distance means how far and Vector means in which direction. Distance Vector routing protocols passperiodic copies of routing table to neighbor routers and accumulate distance vectors. In distance vector routing protocols, routers discover the best path to destination from each neighbor. The routing updates proceed step by step from router to router.
95. Which command is used to display the collection of OSPF link states?
A. show ip ospf link-state
B. show ip ospf lsa database
C. show ip ospf neighbors
D. show ip ospf database
Explanation/Reference:
The “show ip ospf database” command displays the link states. Here is an example:
Here is the lsa database on R2.
R2#show ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count2.2.2.2 2.2.2.2 793 0x80000003 0x004F85
210.4.4.4 10.4.4.4 776 0x80000004 0x005643 1111.111.111.111 111.111.111.111 755
0x80000005 0x0059CA 2133.133.133.133 133.133.133.133 775 0x80000005 0x00B5B1 2 Net
Link States (Area 0)
Link ID ADV Router Age Seq# Checksum10.1.1.1 111.111.111.111 794 0x80000001
0x001E8B10.2.2.3 133.133.133.133 812 0x80000001 0x004BA910.4.4.1 111.111.111.111 755
0x80000001 0x007F1610.4.4.3 133.133.133.133 775 0x80000001 0x00C31F
96. Refer to the exhibit. The technician wants to upload a new IOS in the router while keeping the existing IOS. What is the maximum size of an IOS file that could be loaded if the original IOS is also kept in flash?
A. 3 MB
B. 4 MB
C. 5 MB
D. 7 MB
E. 8 MB
Explanation/Reference:
In this example, there are a total of 8 MB, but 3.8 are being used already, so another file as large as 4MB can be loaded in addition to the original file.
97. If IP routing is enabled, which two commands set the gateway of last resort to the default gateway? (Choose two.)
A. ip default-gateway 0.0.0.0
B. ip route 172.16.2.1 0.0.0.0 0.0.0.0
C. ip default-network 0.0.0.0
D. ip default-route 0.0.0.0 0.0.0.0 172.16.2.1
E. ip route 0.0.0.0 0.0.0.0 172.16.2.1
Explanation/Reference:
Both the “ip default-network” and “ip route 0.0.0.0 0.0.0.0 (next hop)” commands can be used to set the
default gateway in a Cisco router.
98. Refer to the exhibit. The two exhibited devices are the only Cisco devices on the network. The serial network between the two devices has a mask of 255.255.255.252. Given the output that is shown, what three statements are true of these devices? (Choose three.)
A. The Manchester serial address is 10.1.1.1.
B. The Manchester serial address is 10.1.1.2.
C. The London router is a Cisco 2610.
D. The Manchester router is a Cisco 2610.
E. The CDP information was received on port Serial0/0 of the Manchester router.
F. The CDP information was sent by port Serial0/0 of the London router.
Explanation/Reference:
From the output, we learn that the IP address of the neighbor router is 10.1.1.2 and the question stated that the subnet mask of the network between two router is 255.255.255.252. Therefore there are only 2 available hosts in this network (22 ?2 = 2). So we can deduce the ip address (of the serial interface) of Manchester router is 10.1.1.1 -> The platform of the neighbor router is cisco 2610, as shown in the output – > Maybe the most difficult choice of this question is the answer E or F. Please notice that “Interface” refers to the local port on the local router, in this case it is the port of Manchester router, and “Port ID (outgoing port)” refers to the port on the neighbor router.
99. Which parameter would you tune to affect the selection of a static route as a backup, when a dynamic protocol is also being used?
A. hop count
B. administrative distance
C. link bandwidth
D. link delay
E. link cost
Explanation/Reference:
By default the administrative distance of a static route is 1, meaning it will be preferred over all dynamic routing protocols. If you want to have the dynamic routing protocol used and have the static route be used only as a backup, you need to increase the AD of the static route so that it is higher than the dynamic routing protocol.
100. Refer to the exhibit. A network associate has configured OSPF with the command:
City(config-router)# network 192.168.12.64 0.0.0.63 area 0
After completing the configuration, the associate discovers that not all the interfaces are participating in
OSPF. Which three of the interfaces shown in the exhibit will participate in OSPF according to this
configuration statement? (Choose three.)
A. FastEthernet0 /0
B. FastEthernet0 /1
C. Serial0/0
D. Serial0/1.102
E. Serial0/1.103
F. Serial0/1.104
Explanation/Reference:
The “network 192.168.12.64 0.0.0.63 equals to network 192.168.12.64/26. This network has: + Increment:
64 (/26= 1111 1111.1111 1111.1111 1111.1100 0000) + Network address: 192.168.12.64
+ Broadcast address: 192.168.12.127
Therefore all interface in the range of this network will join OSPF.
101. Refer to the exhibit. The Lakeside Company has the internetwork in the exhibit. The administrator would like to reduce the size of the routing table on the Central router. Which partial routing table entry in the Central router represents a route summary that represents the LANs in Phoenix but no additional subnets?
A. 10.0.0.0/22 is subnetted, 1 subnets
D 10.0.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
B. 10.0.0.0/28 is subnetted, 1 subnets
D 10.2.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
C. 10.0.0.0/30 is subnetted, 1 subnets
D 10.2.2.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
D. 10.0.0.0/22 is subnetted, 1 subnets
D 10.4.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
E. 10.0.0.0/28 is subnetted, 1 subnets
D. 10.4.4.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
F. 10.0.0.0/30 is subnetted, 1 subnets
D 10.4.4.4 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
Explanation/Reference:
The 10.4.0.0/22 route includes 10.4.0.0/24, 10.4.1.0/24, 10.4.2.0/24 and 10.4.3.0/24 only.
102. Refer to the graphic. A static route to the 10.5.6.0/24 network is to be configured on the HFD router. Which
commands will accomplish this? (Choose two.)
A. HFD(config)# ip route 10.5.6.0 0.0.0.255 fa0/0
B. HFD(config)# ip route 10.5.6.0 0.0.0.255 10.5.4.6
C. HFD(config)# ip route 10.5.6.0 255.255.255.0 fa0/0
D. HFD(config)# ip route 10.5.6.0 255.255.255.0 10.5.4.6
E. HFD(config)# ip route 10.5.4.6 0.0.0.255 10.5.6.0
F. HFD(config)# ip route 10.5.4.6 255.255.255.0 10.5.6.0
Explanation/Reference:
The simple syntax of static route: ip route destination-network-address subnet-mask {next-hop-IP-address | exit-interface} + destination-network-address: destination network address of the remote network + subnet mask: subnet mask of the destination network + next-hop-IP-address: the IP address of the receiving interface on the next-hop router + exit-interface: the local interface of this router where the packets will go out In the statement “ip route 10.5.6.0 255.255.255.0 fa0/0:
+ 10.5.6.0 255.255.255.0: the destination network
+fa0/0: the exit-interface
103. Before installing a new, upgraded version of the IOS, what should be checked on the router, and which command should be used to gather this information? (Choose two.)
A. the amount of available ROM
B. the amount of available flash and RAM memory
C. the version of the bootstrap software present on the router D. show version
D. show processes
E. show running-config
Explanation/Reference:
When upgrading new version of the IOS we need to copy the IOS to the Flash so first we have to check if the Flash has enough memory or not. Also running the new IOS may require more RAM than the older one so we should check the available RAM too. We can check both with the “show version” command.
104. Which command reveals the last method used to powercycle a router?
A. show reload
B. show boot
C. show running-config
D. show version
Explanation/Reference:
The “show version” command can be used to show the last method to powercycle (reset) a router
105. Which command would you use on a Cisco router to verify the Layer 3 path to a host?
A. tracert address
B. traceroute address
C. telnet address
D. ssh address
Explanation/Reference:
In computing, traceroute is a computer network diagnostic tool for displaying the route (path) and measuring transit delays of packets across an Internet Protocol (IP) network. The history of the route is recorded as the round-trip times of the packets received from each successive host (remote node) in the route (path); the sum of the mean times in each hop indicates the total time spent to establish the connection. Traceroute proceeds unless all (three) sent packets are lost more than twice, then the connection is lost and the route cannot be evaluated. Ping, on the other hand, only computes the final round-trip times from the destination point.
106. What information does a router running a link-state protocol use to build and maintain its topological database? (Choose two.)
A. hello packets
B. SAP messages sent by other routers
C. LSAs from other routers
D. beacons received on point-to-point links
E. routing tables received from other link-state routers
F. TTL packets from designated routers
Explanation/Reference:
Neighbor discovery is the first step in getting a link state environment up and running. In keeping with the friendly neighbor terminology, a Hello protocol is used for this step. The protocol will define a Hello packet format and a procedure for exchanging the packets and processing the information the packets contain.
After the adjacencies are established, the routers may begin sending out LSAs. As the term flooding implies, the advertisements are sent to every neighbor. In turn, each received LSA is copied and forwarded to every neighbor except the one that sent the LSA.
107. Which statements describe the routing protocol OSPF? (Choose three.)
A. It supports VLSM.
B. It is used to route between autonomous systems.
C. It confines network instability to one area of the network.
D. It increases routing overhead on the network.
E. It allows extensive control of routing updates.
F. It is simpler to configure than RIP v2.
Explanation/Reference:
The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth.
OSPF uses flooding to exchange link-state updates between routers. Any change in routing information is flooded to all routers in the network. Areas are introduced to put a boundary on the explosion of link-state updates. Flooding and calculation of the Dijkstra algorithm on a router is limited to changes within an area.
108. Refer to the exhibit. A network administrator configures a new router and enters the copy startupconfig running-config command on the router. The network administrator powers down the router and sets it up at a remote location. When the router starts, it enters the system configuration dialog as shown. What is the cause of the problem?
A. The network administrator failed to save the configuration.
B. The configuration register is set to 0x2100.
C. The boot system flash command is missing from the configuration.
D. The configuration register is set to 0x2102.
E. The router is configured with the boot system startup command.
Explanation/Reference:
The “System Configuration Dialog” appears only when no startup configuration file is found. The network administrator has made a mistake because the command “copy startup-config running- config” will copy the startup config (which is empty) over the running config (which is configured by the administrator). So everything configured was deleted. Note: We can tell the router to ignore the start-up configuration on the next reload by setting the register to 0?142. This will make the “System Configuration Dialog” appear at the next reload.
109. Refer to the exhibit. Which WAN protocol is being used?
A. ATM
B. HDLC
C. Frame-relay
D. PPP
Explanation/Reference:
This question is to examine the show int command. According to the information provided in the exhibit, we can know that the data link protocol used in this network is the Frame Relay protocol. “LMI enq sent…”
110. What is the default administrative distance of OSPF?
A. 90
B. 100
C. 110
D. 120
Explanation/Reference:
Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value. Default Distance Value Table This table lists the administrative distance default values of the protocols that Cisco supports:
Route Source
Default Distance Values
Connected interface
Static route
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route External Border Gateway Protocol
(BGP)
Internal EIGRP
IGRP
OSPF
Intermediate System-to-Intermediate System (IS-IS)
Routing Information Protocol (RIP)
Exterior Gateway Protocol (EGP)
On Demand Routing (ODR)
External EIGRP
Internal BGP
Unknown*
111. Which characteristics are representative of a link-state routing protocol? (Choose three.)
A. provides common view of entire topology
B. exchanges routing tables with neighbors
C. calculates shortest path
D. utilizes event-triggered updates
E. utilizes frequent periodic updates
Explanation/Reference:
Each of routers running link-state routing protocol learns paths to all the destinations in its “area” so we can say although it is a bit unclear.
Link-state routing protocols generate routing updates only (not the whole routing table) when a change occurs in the network topology so Link-state routing protocol like OSPF uses Dijkstra algorithm to calculate the shortest path -> . Unlike
Distance vector routing protocol (which utilizes frequent periodic updates), link-state routing protocol utilizes event-triggered updates (only sends update when a change occurs) ->
112. Refer to the exhibit. Based on the exhibited routing table, how will packets from a host within the 192.168.10.192/26 LAN be forwarded to 192.168.10.1?
A. The router will forward packets from R3 to R2 to R1.
B. The router will forward packets from R3 to R1 to R2.
C. The router will forward packets from R3 to R2 to R1 AND from R3 to R1.
D. The router will forward packets from R3 to R1.
Explanation/Reference:
From the routing table we learn that network 192.168.10.0/30 is learned via 2 equal-cost paths (192.168.10.9 &192.168.10.5) -> traffic to this network will be load-balancing.
113. Refer to the exhibit. C-router is to be used as a “router-on-a-stick” to route between the VLANs. All the interfaces have been properly configured and IP routing is operational. The hosts in the VLANs have been configured with the appropriate default gateway. What is true about this configuration?
A. These commands need to be added to the configuration:
C-router(config)# router eigrp 123
C-router(config-router)# network 172.19.0.0
B. These commands need to be added to the configuration:
C-router(config)# router ospf 1
C-router(config-router)# network 172.19.0.0 0.0.3.255 area 0
C. These commands need to be added to the configuration:
C-router(config)# router rip
C-router(config-router)# network 172.19.0.0
D. No further routing configuration is required.
114. Which command would you configure globally on a Cisco router that would allow you to view directly connected Cisco devices?
A. enable cdp
B. cdp enable
C. cdp run
D. run cdp
Explanation/Reference:
CDP is enabled on Cisco routers by default. If you prefer not to use the CDP capability, disable it with the no cdp run command. In order to reenable CDP, use the cdp run command in global configuration mode. The “cdp enable” command is an interface command, not global.
115. Refer to the exhibit. Why is flash memory erased prior to upgrading the IOS image from the TFTP server?
A. The router cannot verify that the Cisco IOS image currently in flash is valid.
B. Flash memory on Cisco routers can contain only a single IOS image.
C. Erasing current flash content is requested during the copy dialog.
D. In order for the router to use the new image as the default, it must be the only IOS image in flash.
Explanation/Reference:
During the copy process, the router asked “Erasing flash before copying? [confirm]” and the administrator confirmed (by pressing Enter) so the flash was deleted. Note: In this case, the flash has enough space to copy a new IOS without deleting the current one. The current IOS is deleted just because the administrator wants to do so. If the flash does not have enough space you will see an error message like this: %Error copying tftp://192.168.2.167/ c1600-k8sy-mz.l23-16a.bin (Not enough space on device)
116. Refer to the exhibit. According to the routing table, where will the router send a packet destined for 10.1.5.65?
A. 10.1.1.2
B. 10.1.2.2
C. 10.1.3.3
D. 10.1.4.4
Explanation/Reference:
The destination IP address 10.1.5.65 belongs to 10.1.5.64/28, 10.1.5.64/29 & 10.1.5.64/27 subnets but the “longest prefix match” algorithm will choose the most specific subnet mask -> the prefix “/29 will be chosen to route the packet. Therefore the next-hop should be 10.1.3.3 -> .
117. Refer to the exhibit. Which address and mask combination represents a summary of the routes learned by EIGRP?
A. 192.168.25.0 255.255.255.240
B. 192.168.25.0 255.255.255.252
C. 192.168.25.16 255.255.255.240
D. 192.168.25.16 255.255.255.252
E. 192.168.25.28 255.255.255.240
F. 192.168.25.28 255.255.255.252
Explanation/Reference:
The binary version of 20 is 10100.
The binary version of 16 is 10000.
The binary version of 24 is 11000.
The binary version of 28 is 11100.
The subnet mask is /28. The mask is 255.255.255.240.
Note: From the output above, EIGRP learned 4 routes and we need to find out the summary of them:
+ 192.168.25.16
+ 192.168.25.20
+ 192.168.25.24
+ 192.168.25.28
-> The increment should bE. 28 ?16 = 12 but 12 is not an exponentiation of 2 so we must choose 16 (24).
Therefore the subnet mask is /28 (=1111 1111.1111 1111.1111 1111.11110000) = 255.255.255.240
So the best answer should be 192.168.25.16 255.255.255.240
118. Refer to the exhibit. Assuming that the entire network topology is shown, what is the operational status of the interfaces of R2 as indicated by the command output shown?
A. One interface has a problem.
B. Two interfaces have problems.
C. The interfaces are functioning correctly.
D. The operational status of the interfaces cannot be determined from the output shown.
Explanation/Reference:
The output shown shows normal operational status of the router’s interfaces. Serial0/0 is down because it has been disabled using the “shutdown” command.
119. Which two locations can be configured as a source for the IOS image in the boot system command? (Choose two.)
A. RAM
B. NVRAM
C. flash memory
D. HTTP server
E. TFTP server
F. Telnet server
Explanation/Reference:
The following locations can be configured as a source for the IOS image:
+ Flash (the default location)
+ TFTP server
+ ROM (used if no other source is found)
120. Refer to the exhibit. Given the output for this command, if the router ID has not been manually set, what router ID will OSPF use for this router?
A. 10.1.1.2
B. 10.154.154.1
C. 172.16.5.1
D. 192.168.5.3
Explanation/Reference:
The highest IP address of all loopback interfaces will be chosen -> Loopback 0 will be chosen as the router
ID.
121. Which two statements describe the process identifier that is used in the command to configure OSPF on a router? (Choose two.) Router(config)# router ospf 1
A. All OSPF routers in an area must have the same process ID
B. Only one process number can be used on the same router.
C. Different process identifiers can be used to run multiple OSPF processes
D. The process number can be any number from 1 to 65,535.
E. Hello packets are sent to each neighbor to determine the processor identifier.
Explanation/Reference:
Multiple OSPF processes can be configured on a router using multiple process ID’s.
The valid process ID’s are shown below:
Edge-B(config)#router ospf ?
<1-65535> Process ID
122. Refer to the exhibit. What commands must be configured on the 2950 switch and the router to allow communication between host 1 and host 2? (Choose two.)
A. Router(config)# interface fastethernet 0/0
Router(config-if)# ip address 192.168.1.1 255.255.255.0 Router(config-if)#
no shut down
B. Router(config)# interface fastethernet 0/0
Router(config-if)# no shut down
Router(config)# interface fastethernet 0/0.1
Router(config-subif)# encapsulation dot1q 10
Router(config-subif)# ip address 192.168.10.1 255.255.255.0
Router(config)# interface fastethernet 0/0.2
Router(config-subif)# encapsulation dot1q 20
Router(config-subif)# ip address 192.168.20.1 255.255.255.0
C. Router(config)# router eigrp 100
Router(config-router)# network 192.168.10.0
Router(config-router)# network 192.168.20.0
D. Switch1(config)# vlan database Switch1(config-vlan)# vtp domain XYZ
Switch1(config-vlan)# vtp server
E. Switch1(config)# interface fastethernet 0/1 Switch1(config-if)# switchport
mode trunk F. Switch1(config)# interface vlan 1 Switch1(config-if)# ip
default-gateway 192.168.1.1
Explanation/Reference:
The router will need to use subinterfaces, where each subinterface is assigned a VLAN and IP address for each VLAN. On the switch, the connection to the router need to be configured as a trunk using the switchport mode trunk command and it will need a default gateway for VLAN 1.
123. Refer to the exhibit. For what two reasons has the router loaded its IOS image from the location that is shown? (Choose two.)
A. Router1 has specific boot system commands that instruct it to load IOS from a TFTP server.
B. Router1 is acting as a TFTP server for other routers.
C. Router1 cannot locate a valid IOS image in flash memory.
D. Router1 defaulted to ROMMON mode and loaded the IOS image from a TFTP server.
E. Cisco routers will first attempt to load an image from TFTP for management purposes
Explanation/Reference:
The loading sequence of CISCO IOS is as follows:
Booting up the router and locating the Cisco IOS
POST (power on self test)
Bootstrap code executed
Check Configuration Register value (NVRAM) which can be modified using the config-register
command
= ROM Monitor mode
= ROM IOS
– 15 = startup-config in NVRAM
4. Startup-config filE. Check for boot system commands (NVRAM) If boot system commands in startup-config a. Run boot system commands in order they appear in startup-config to locate the IOS b. [If boot system commands fail, use default fallback sequence to locate the IOS (Flash, TFTP, ROM)?] If no boot system commands in startup-config use the default fallback sequence in locating the IOS:
Flash (sequential)
TFTP server (netboot)
ROM (partial IOS) or keep retrying TFTP depending upon router model
5. If IOS is loaded, but there is no startup-config file, the router will use the default fallback sequence for
locating the IOS and then it will enter setup mode or the setup dialogue.
124. Refer to the exhibit. What can be determined about the router from the console output?
A. No configuration file was found in NVRAM.
B. No configuration file was found in flash.
C. No configuration file was found in the PCMCIA card.
D. Configuration file is normal and will load in 15 seconds.
Explanation/Reference:
When no startup configuration file is found in NVRAM, the System Configuration Dialog will appear to ask if we want to enter the initial configuration dialog or not.
125. Which three elements must be used when you configure a router interface for VLAN trunking? (Choose three.)
A. one physical interface for each subinterface
B. one IP network or subnetwork for each subinterface
C. a management domain for each subinterface
D. subinterface encapsulation identifiers that match VLAN tags
E. one subinterface per VLAN
F. subinterface numbering that matches VLAN tags
Explanation/Reference:
This scenario is commonly called a router on a stick. A short, well written article on this operation can be
found here: http://www.thebryantadvantage.com/RouterOnAStickCCNACertificationExamTutorial.htm
126. Which commands are required to properly configure a router to run OSPF and to add network 192.168.16.0/24 to OSPF area 0? (Choose two.)
A. Router(config)# router ospf 0
B. Router(config)# router ospf 1
C. Router(config)# router ospf area 0
D. outer(config-router)# network 192.168.16.0 0.0.0.255 0
E. Router(config-router)# network 192.168.16.0 0.0.0.255 area 0
F. Router(config-router)# network 192.168.16.0 255.255.255.0 area 0
Explanation/Reference:
In the router ospf command, the ranges from 1 to 65535 so o is an invalid number -> but To configure OSPF, we need a wildcard in the “network” statement, not a subnet mask. We also need to assgin an area to this process ->
127. A router receives information about network 192.168.10.0/24 from multiple sources. What will the router consider the most reliable information about the path to that network?
A. a directly connected interface with an address of 192.168.10.254/24
B. a static route to network 192.168.10.0/24
C. a RIP update for network 192.168.10.0/24
D. an OSPF update for network 192.168.0.0/16
E. a default route with a next hop address of 192.168.10.1
F. a static route to network 192.168.10.0/24 with a local serial interface configured as the next hop
Explanation/Reference:
When there is more than one way to reach a destination, it will choose the best one based on a couple of things. First, it will choose the route that has the longest match; meaning the most specific route. So, in this case the /24 routes will be chosen over the /16 routes. Next, from all the /24 routes it will choose the one with the lowest administrative distance. Directly connected routes have an AD of 1 so this will be the route
chosen.
128. What is the default maximum number of equal-cost paths that can be placed into the routing table of aCisco OSPF router?
A. 2
B. 4
C. 16
D. unlimited
Explanation/Reference:
maximum-paths (OSPF) To control the maximum number of parallel routes that Open Shortest Path First (OSPF) can support, use the maximum-paths command. Syntax Description maximum Maximum number of parallel routes that OSPF can install in a routing table. The range is from 1 to 16
routes.
Command Default
8 paths
129. Which command shows your active Telnet connections?
A. show cdp neigbors
B. show session
C. show users
D. show vty logins
Explanation/Reference:
The “show users” shows telnet/ssh connections to your router while “show sessions” shows telnet/ssh connections from your router (to other devices). The question asks about “your active Telnet connections”, meaning connections from your router so the answer should be A.
130. Refer to the exhibit. What statement is true of the configuration for this network?
A. The configuration that is shown provides inadequate outside address space for translation of the
number of inside addresses that are supported.
B. Because of the addressing on interface FastEthernet0/1, the Serial0/0 interface address will not support
the NAT configuration as shown.
C. The number 1 referred to in the ip nat inside source command references access-list number 1.
D. ExternalRouter must be configured with static routes to networks 172.16.1.0/24 and 172.16.2.0/24.
131. Which type of EIGRP route entry describes a feasible successor?
A. a backup route, stored in the routing table
B. a primary route, stored in the routing table
C. a backup route, stored in the topology table
D. a primary route, stored in the topology table
Explanation/Reference:
EIGRP uses the Neighbor Table to list adjacent routers. The Topology Table list all the learned routers to destination whilst the Routing Table contains the best route to a destination, which is known as the Successor. The Feasible Successor is a backup route to a destination which is kept in the Topology Table.
132. Which statement describes the process of dynamically assigning IP addresses by the DHCP server?
A. Addresses are allocated after a negotiation between the server and the host to determine the length of
the agreement.
B. Addresses are permanently assigned so that the hosts uses the same address at all times.
C. Addresses are assigned for a fixed period of time, at the end of the period, a new request for an
address must be made.
D. Addresses are leased to hosts, which periodically contact the DHCP server to renew the lease.
133. What are two benefits of using NAT? (Choose two.)
A. NAT facilitates end-to-end communication when IPsec is enabled.
B. NAT eliminates the need to re-address all hosts that require external access.
C. NAT conserves addresses through host MAC-level multiplexing.
D. Dynamic NAT facilitates connections from the outside of the network.
E. NAT accelerates the routing process because no modifications are made on the packets
F. NAT protects network security because private networks are not advertised.
Explanation/Reference:
By not revealing the internal Ip addresses, NAT adds some security to the inside network -> F is correct.
NAT has to modify the source IP addresses in the packets -> E is not correct.
Connection from the outside of the network through a “NAT” network is more difficult than a more network because IP addresses of inside hosts are hidden -> C is not correct.
In order for IPsec to work with NAT we need to allow additional protocols, including Internet Key Exchange
(IKE), Encapsulating Security Payload (ESP) and Authentication Header (AH) -> more complex -> A is not
correct.
By allocating specific public IP addresses to inside hosts, NAT eliminates the need to re-address the inside
hosts -> B is correct.
NAT does conserve addresses but not through host MAC-level multiplexing. It conserves addresses by allowing many private IP addresses to use the same public IP address to go to the Internet -> C is not correct.
134. On which options are standard access lists based?
A. destination address and wildcard mask
B. destination address and subnet mask
C. source address and subnet mask
D. source address and wildcard mask
Explanation/Reference:
Standard ACL’s only examine the source IP address/mask to determine if a match is made. Extended ACL’s examine the source and destination address, as well as port information.
135. A network engineer wants to allow a temporary entry for a remote user with a specific username and password so that the user can access the entire network over the Internet. Which ACL can be used?
A. standard
B. extended
C. dynamic
D. reflexive
Explanation/Reference:
We can use a dynamic access list to authenticate a remote user with a specific username and password.
The authentication process is done by the router or a central access server such as a TACACS+ or RADIUS server. The configuration of dynamic ACL can be read here: http://www.cisco.com/en/US/tech/tk583/tk822/technologies_tech_note09186a0080094524.shtml
136.How does a DHCP server dynamically assign IP addresses to hosts?
A. Addresses are permanently assigned so that the host uses the same address at all times.
B. Addresses are assigned for a fixed period of time. At the end of the period, a new request for an
address must be made, and another address is then assigned.
C. Addresses are leased to hosts. A host will usually keep the same address by periodically contacting thDHCP server to renew the lease.
D. Addresses are allocated after a negotiation between the server and the host to determine the length of
the agreement.
Explanation/Reference:
DHCP works in a client/server mode and operates like any other client/server relationship. When a PC connects to a DHCP server, the server assigns or leases an IP address to that PC. The PC connects to the network with that leased IP address until the lease expires. The host must contact the DHCP server periodically to extend the lease. This lease mechanism ensures that hosts that move or power off do not hold onto addresses that they do not need. The DHCP server returns these addresses to the address pool and reallocates them as necessary.
137. Refer to the exhibit. Which rule does the DHCP server use when there is an IP address conflict?
A. The address is removed from the pool until the conflict is resolved.
B. The address remains in the pool until the conflict is resolved.
C. Only the IP detected by Gratuitous ARP is removed from the pool
D. Only the IP detected by Ping is removed from the pool.
E. The IP will be shown, even after the conflict is resolved.
Explanation/Reference:
An address conflict occurs when two hosts use the same IP address. During address assignment, DHCP checks for conflicts using ping and gratuitous ARP. If a conflict is detected, the address is removed from the pool. The address will not be assigned until the administrator resolves the conflict.
http://www.cisco.com/en/US/docs/ios/12_1/iproute/configuration/guide/1cddhcp.html
138. Which two tasks does the Dynamic Host Configuration Protocol perform? (Choose two.)
A. Set the IP gateway to be used by the network.
B. Perform host discovery used DHCPDISCOVER message.
C. Configure IP address parameters from DHCP server to a host.
D. Provide an easy management of layer 3 devices.
E. Monitor IP performance using the DHCP server.
F. Assign and renew IP address from the default pool.
Explanation/Reference:
The Dynamic Host Configuration Protocol (DHCP) is a network protocol used to configure devices that are connected to a network (known as hosts) so they can communicate on that network using the Internet Protocol (IP). It involves clients and a server operating in a clientserver model. DHCP servers assigns IP addresses from a pool of addresses and also assigns other parameters such as DNS and default gateways to hosts.
139, Refer to the exhibit. What statement is true of the configuration for this network?
A. The configuration that is shown provides inadequate outside address space for translation of the
number of inside addresses that are supported.
B. Because of the addressing on interface FastEthernet0/1, the Serial0/0 interface address will not support the NAT configuration as shown.
C. The number 1 referred to in the ip nat inside source command references access-list number 1.
D. ExternalRouter must be configured with static routes to networks 172.16.1.0/24 and 172.16.2.0/24.
140. When a DHCP server is configured, which two IP addresses should never be assignable to hosts? (Choose two.)
A. network or subnetwork IP address
B. broadcast address on the network
C. IP address leased to the LAN
D. IP address used by the interfaces
E. manually assigned address to the clients
F. designated IP address to the DHCP server
Explanation/Reference:
Network or subnetwork IP address (for example 11.0.0.0/8 or 13.1.0.0/16) and broadcast address (for example 23.2.1.255/24) should never be assignable to hosts. When try to assign these addresses to hosts, you will receive an error message saying that they can’t be assignable.
141. Which two statements about static NAT translations are true? (Choose two.)
A. They allow connections to be initiated from the outside.
B. They require no inside or outside interface markings because addresses are statically defined.
C. They are always present in the NAT table.
D. They can be configured with access lists, to allow two or more connections to be initiated from the
outside.
Explanation/Reference:
Static NAT is to map a single outside IP address to a single inside IP address. This is typically done to allow incoming connections from the outside (Internet) to the inside. Since these are static, they are always present in the NAT table even if they are not actively in use.
142. Which statement about access lists that are applied to an interface is true?
A. You can place as many access lists as you want on any interface.
B. You can apply only one access list on any interface.
C. You can configure one access list, per direction, per Layer 3 protocol.
D. You can apply multiple access lists with the same protocol or in different directions.
Explanation/Reference:
We can have only 1 access list per protocol, per direction and per interface. It means: + We can not have 2 inbound access lists on an interface + We can have 1 inbound and 1 outbound access list on an interface
143. Which item represents the standard IP ACL?
A. access-list 110 permit ip any any
B. access-list 50 deny 192.168.1.1 0.0.0.255
C. access list 101 deny tcp any host 192.168.1.1
D. access-list 2500 deny tcp any host 192.168.1.1 eq 22
Explanation/Reference:
The standard access lists are ranged from 1 to 99 and from 1300 to 1999 so only access list 50 is a standard access list.
144. A network administrator is configuring ACLs on a Cisco router, to allow traffic from hosts on networks 192.168.146.0, 192.168.147.0, 192.168.148.0, and 192.168.149.0 only. Which two ACL statements, when combined, would you use to accomplish this task? (Choose two.)
A. access-list 10 permit ip 192.168.146.0 0.0.1.255
B. access-list 10 permit ip 192.168.147.0 0.0.255.255
C. access-list 10 permit ip 192.168.148.0 0.0.1.255
D. access-list 10 permit ip 192.168.149.0 0.0.255.255
E. access-list 10 permit ip 192.168.146.0 0.0.0.255
F. access-list 10 permit ip 192.168.146.0 255.255.255.0
Explanation/Reference:
access-list 10 permit ip 192.168.146.0 0.0.1.255 will include the 192.168.146.0 and 192.168.147.0 subnets, while access-list 10 permit ip 192.168.148.0 0.0.1.255 will include
145. What can be done to secure the virtual terminal interfaces on a router? (Choose two.)
A. Administratively shut down the interface.
B. Physically secure the interface.
C. Create an access list and apply it to the virtual terminal interfaces with the access-group command.
D. Configure a virtual terminal password and login process.
E. Enter an access list and apply it to the virtual terminal interfaces using the access-class command.
Explanation/Reference:
It is a waste to administratively shut down the interface. Moreover, someone can still access the virtual terminal interfaces via other interfaces -> We can not physically secure a virtual interface because it is “virtual” -> To apply an access list to a virtual terminal interface we must use the “access-class” command. The “access-group” command is only used to apply an access list to a physical interface -> C is not correct. The most simple way to secure the virtual terminal interface is to configure a username & password to prevent unauthorized login.
146. Which two commands correctly verify whether port security has been configured on port FastEthernet 0/12 on a switch? (Choose two.)
A. SW1#show port-secure interface FastEthernet 0/12
B. SW1#show switchport port-secure interface FastEthernet 0/12
C. SW1#show running-config
D. SW1#show port-security interface FastEthernet 0/12
E. SW1#show switchport port-security interface FastEthernet 0/12
Explanation/Reference:
We can verify whether port security has been configured by using the “show running-config” or “show port- security interface ” for more detail. An example of the output of “show port-security interface ” command is shown below:
147. Refer to the exhibit. The following commands are executed on interface fa0/1 of 2950Switch.
2950Switch(config-if)# switchport port-security
2950Switch(config-if)# switchport port-security mac-address sticky
2950Switch(config-if)# switchport port-security maximum 1
The Ethernet frame that is shown arrives on interface fa0/1.
What two functions will occur when this frame is received by 2950Switch? (Choose two.)
A. The MAC address table will now have an additional entry of fa0/1 FFFF.FFFF.FFFF.
B. Only host A will be allowed to transmit frames on fa0/1.
C. This frame will be discarded when it is received by 2950Switch.
D. All frames arriving on 2950Switch with a destination of 0000.00aa.aaaa will be forwarded out fa0/1.
E. Hosts B and C may forward frames out fa0/1 but frames arriving from other switches will not be
forwarded out fa0/1.
F. Only frames from source 0000.00bb.bbbb, the first learned MAC address of 2950Switch, will be
Explanation/Reference:
The configuration shown here is an example of port security, specifically port security using sticky addresses. You can use port security with dynamically learned and static MAC addresses to restrict a port’s ingress traffic by limiting the MAC addresses that are allowed to send traffic into the port. When you assign secure MAC addresses to a secure port, the port does not forward ingress traffic that has source addresses outside the group of defined addresses. If you limit the number of secure MAC addresses to one and assign a single secure MAC address, the device attached to that port has the full bandwidth of the port. Port security with sticky MAC addresses provides many of the same benefits as port security with static MAC addresses, but sticky MAC addresses can be learned dynamically. Port security with sticky MAC addresses retains dynamically learned MAC addresses during a link-down condition.
148. What will be the result if the following configuration commands are implemented on a Cisco switch?
Switch(config-if)# switchport port-security
Switch(config-if)# switchport port-security mac-address sticky
A. A dynamically learned MAC address is saved in the startup-configuration file.
B. A dynamically learned MAC address is saved in the running-configuration file.
C. A dynamically learned MAC address is saved in the VLAN database.
D. Statically configured MAC addresses are saved in the startup-configuration file if frames from that
address are received.
E. Statically configured MAC addresses are saved in the running-configuration file if frames from that
address are received.
Explanation/Reference:
In the interface configuration mode, the command switchport port-security mac-address sticky enables sticky learning. When entering this command, the interface converts all the dynamic secure MAC addresses to sticky secure MAC addresses.
149. The network administrator cannot connect to Switch1 over a Telnet session, although the hosts attached to Switch1 can ping the interface Fa0/0 of the router. Given the information in the graphic and assuming that the router and Switch2 are configured properly, which of the following commands should be issued on Switch1 to correct this problem?
A. Switch1(config)# line con0
Switch1(config-line)# password cisco
Switch1(config-line)#login
B. Switch1(config)# interface fa0/1
Switch1(config-if)# ip address 192.168.24.3 255.255.255.0
C. Switch1(config)# ip default-gateway 192.168.24.1
D. Switch1(config)# interface fa0/1
Switch1(config-if)# duplex full
Switch1(config-if)# speed 100
E. Switch1(config)# interface fa0/1
Switch1(config-if)# switchport mode trunk
Explanation/Reference:
Since we know hosts can reach the router through the switch, we know that connectivity, duplex. Speed, etc. are good. However, for the switch itself to reach networks outside the local one, the ip default-gateway command must be used.
150. Refer to the exhibit. Which of these statements correctly describes the state of the switch once the boot process has been completed?
A. As FastEthernet0/12 will be the last to come up, it will be blocked by STP.
B. Remote access management of this switch will not be possible without configuration change.
C. More VLANs will need to be created for this switch.
D. The switch will need a different IOS code in order to support VLANs and STP.
Explanation/Reference:
Notice the line, which says “Interface VLAN1, changed state to administratively down”. This shows that VLAN1 is shut down. Hence remote management of this switch is not possible unless VLAN1 is brought back up. Since VLAN1 is the only interface shown in the output, you have to assume that no other VLAN interface has been configured with an IP Address.
151. Refer to exhibit. A network administrator cannot establish a Telnet session with the indicated router. What is the cause of this failure?
A. A Level 5 password is not set.
B. An ACL is blocking Telnet access.
C. The vty password is missing.
D. The console password is missing.
Explanation/Reference:
The login keyword has been set, but not password. This will result in the “password required, but none set” message to users trying to telnet to this router.
152. Refer to the exhibit. When running EIGRP, what is required for RouterA to exchange routing updates with RouterC?
A. AS numbers must be changed to match on all the routers
B. Loopback interfaces must be configured so a DR is elected
C. The no auto-summary command is needed on Router A and Router C
D. Router B needs to have two network statements, one for each connected network
Explanation/Reference:
This question is to examine the understanding of the interaction between EIGRP routers. The following information must be matched so as to create neighborhood. EIGRP routers to establish, must match the following information: 1. AS Number; 2. K value.
153. A router has two Fast Ethernet interfaces and needs to connect to four VLANs in the local network. How can you accomplish this task, using the fewest physical interfaces and without decreasing network performance?
A. Use a hub to connect the four VLANS with a Fast Ethernet interface on the router.
B. Add a second router to handle the VLAN traffic.
C. Add two more Fast Ethernet interfaces.
D. Implement a router-on-a-stick configuration.
Explanation/Reference:
A router on a stick allows you to use sub-interfaces to create multiple logical networks on a single physical interface.
154. Users on the 172.17.22.0 network cannot reach the server located on the 172.31.5.0 network. The network administrator connected to router Coffee via the console port, issued the show ip route command, and was able to ping the server .
on the output of the show ip route command and the topology shown in the graphic, what is the cause of the failure?
A. The network has not fully converged.
B. IP routing is not enabled.
C. A static route is configured incorrectly
D. The FastEthernet interface on Coffee is disabled.
E. The neighbor relationship table is not correctly updated.
F. The routing table on Coffee has not updated .
Explanation/Reference:
The default route or the static route was configured with incorrect next-hop ip address 172.19.22.2 The correct ip address will be 172.18.22.2 to reach server located on 172.31.5.0 network. Ip route 0.0.0.0 0.0.0.0 172.18.22.2
155. A network administrator is trying to add a new router into an established OSPF network. The networks attached to the new router do not appear in the routing tables of the other OSPF routers. Given the information in the partial configuration shown below, what configuration error is causing this problem?
Router(config)# router ospf 1
Router(config-router)# network 10.0.0.0 255.0.0.0 area 0
A. The process id is configured improperly.
B. The OSPF area is configured improperly.
C. The network wildcard mask is configured improperly.
D. The network number is configured improperly.
E. The AS is configured improperly.
F. The network subnet mask is configured improperly.
Explanation/Reference:
When configuring OSPF, the mask used for the network statement is a wildcard mask similar to an access list. In this specific example, the correct syntax would have been “network 10.0.0.0 0.0.0.255 area 0.”
156. Which Cisco Catalyst feature automatically disables the port in an operational PortFast upon receipt of a BPDU?
A. BackboneFast B. UplinkFast
C. Root Guard
D. BPDU Guard
E. BPDU Filter
Explanation/Reference:
We only enable PortFast feature on access ports (ports connected to end stations). But if someone does not know he can accidentally plug that port to another switch and a loop may occur when BPDUs are being transmitted and received on these ports. With BPDU Guard, when a PortFast receives a BPDU, it will be shut down to prevent a loop.
157. When you are troubleshooting an ACL issue on a router, which command would you use to verify which interfaces are affected by the ACL?
A. show ip access-lists
B. show access-lists
C. show interface
D. show ip interface
E. list ip interface
Explanation/Reference:
Incorrect answer:
show ip access-lists does not show interfaces affected by an ACL.
158. Host 1 is trying to communicate with Host 2. The e0 interface on Router C is down. Which of the following are true? (Choose two.)
A. Router C will use ICMP to inform Host 1 that Host 2 cannot be reached.
B. Router C will use ICMP to inform Router B that Host 2 cannot be reached.
C. Router C will use ICMP to inform Host 1, Router A, and Router B that Host 2 cannot be reached.
D. Router C will send a Destination Unreachable message type.
E. Router C will send a Router Selection message type.
F. Router C will send a Source Quench message type.
Explanation/Reference:
Host 1 is trying to communicate with Host 2. The e0 interface on Router C is down. Router C will send ICMP packets to inform Host 1 that Host 2 cannot be reached.
159. Refer to the exhibit. When running EIGRP, what is required for RouterA to exchange routing updates with RouterC?
A. AS numbers must be changed to match on all the routers
B. Loopback interfaces must be configured so a DR is elected
C. The no auto-summary command is needed on Router A and Router C
D. Router B needs to have two network statements, one for each connected network
Explanation/Reference:
This question is to examine the understanding of the interaction between EIGRP routers. The following information must be matched so as to create neighborhood. EIGRP routers to establish, must match the following information: 1. AS Number; 2. K value.
160. Cisco Catalyst switches CAT1 and CAT2 have a connection between them using ports FA0/13. An 802.1Q trunk is configured between the two switches. On CAT1, VLAN 10 is chosen as native, but on CAT2 the native VLAN is not specified. What will happen in this scenario?
A. 802.1Q giants frames could saturate the link.
B. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send untagged frames.
C. A native VLAN mismatch error message will appear.
D. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send tagged frames.
Explanation/Reference:
A “native VLAN mismatch” error will appear by CDP if there is a native VLAN mismatch on an 802.1Q link. “VLAN mismatch” can cause traffic from one vlan to leak into another vlan.
161. Refer to the exhibit. A network technician is asked to design a small network with redundancy. The exhibit represents this design, with all hosts configured in the same VLAN. What conclusions can be made about this design?
A. This design will function as intended.
B. Spanning-tree will need to be used.
C. The router will not accept the addressing scheme.
D. The connection between switches should be a trunk.
E. The router interfaces must be encapsulated with the 802.1Q protocol.
Explanation/Reference:
Each interface on a router must be in a different network. If two interfaces are in the same network, the router will not accept it and show error when the administrator assigns it.
162. Refer to the exhibit. A technician is troubleshooting host connectivity issues on the switches. The hosts in VLANs 10 and 15 on Sw11 are unable to communicate with hosts in the same VLANs on Sw12. Hosts in the Admin VLAN are able to communicate. The port-to-VLAN assignments are identical on the two switches. What could be the problem?
A. The Fa0/1 port is not operational on one of the switches.
B. The link connecting the switches has not been configured as a trunk.
C. At least one port needs to be configured in VLAN 1 for VLANs 10 and 15 to be able to communicate.
D. Port FastEthernet 0/1 needs to be configured as an access link on both switches.
E. A router is required for hosts on SW11 in VLANs 10 and 15 to communicate with hosts in the same
VLAN on Sw12.
Explanation/Reference:
In order for hosts in the same VLAN to communicate with each other over multiple switches, those switches need to be configured as trunks on their connected interfaces so that they can pass traffic from multiple VLANs.
163. Refer to the exhibit. The Bigtime router is unable to authenticate to the Littletime router. What is the cause of the problem?
A. The usernames are incorrectly configured on the two routers.
B. The passwords do not match on the two routers.
C. CHAP authentication cannot be used on a serial interface. D. The routers cannot be connected from interface S0/0 to interface S0/0.
E. With CHAP authentication, one router must authenticate to another router. The routers cannot be configured to authenticate to each other.
Explanation/Reference:
With CHAP authentication, the configured passwords must be identical on each router. Here, it is configured as little123 on one side and big123 on the other.
164. Refer to the exhibit. Given this output for SwitchC, what should the network administrator’s next action be?
A. Check the trunk encapsulation mode for SwitchC’s fa0/1 port.
B. Check the duplex mode for SwitchC’s fa0/1 port.
C. Check the duplex mode for SwitchA’s fa0/2 port.
D. Check the trunk encapsulation mode for SwitchA’s fa0/2 port.
Explanation/Reference:
Here we can see that this port is configured for full duplex, so the next step would be to check the duplex setting of the port on the other switch. A mismatched trunk encapsulation would not result in input errors and CRC errors.
165. What will happen if a private IP address is assigned to a public interface connected to an ISP?
A. Addresses in a private range will be not be routed on the Internet backbone.
B. Only the ISP router will have the capability to access the public network.
C. The NAT process will be used to translate this address to a valid IP address.
D. A conflict of IP addresses happens, because other public routers can use the same range.
Explanation/Reference:
Private RFC 1918 IP addresses are meant to be used by organizations locally within their own network only, and can not be used globally for Internet use.
166. Refer to the exhibit. An attempt to deny web access to a subnet blocks all traffic from the subnet. Which interface command immediately removes the effect of ACL 102?
A. no ip access-class 102 in
B. no ip access-class 102 out
C. no ip access-group 102 in
D. no ip access-group 102 out
E. no ip access-list 102 in
Explanation/Reference:
Now let’s find out the range of the networks on serial link:
For the network 192.168.1.62/27:
Increment: 32
Network address: 192.168.1.32
Broadcast address: 192.168.1.63 For the network 192.168.1.65/27:
Increment: 32
Network address: 192.168.1.64
Broadcast address: 192.168.1.95
-> These two IP addresses don’t belong to the same network and they can’t see each other
167. Which router IOS commands can be used to troubleshoot LAN connectivity problems? (Choose three.)
A. ping
B. tracert C. ipconfig
D. show ip route
E. winipcfg
F. show interfaces
Explanation/Reference:
Ping, show ip route, and show interfaces are all valid troubleshooting IOS commands. Tracert, ipconfig, and winipcfg are PC commands, not IOS.
168. A network administrator is troubleshooting the OSPF configuration of routers R1 and R2. The routers cannot establish an adjacency relationship on their common Ethernet link.
The graphic shows the output of the show ip ospf interface e0 command for routers R1 and R2. Based on the information in the graphic, what is the cause of this problem?
A. The OSPF area is not configured properly.
B. The priority on R1 should be set higher.
C. The cost on R1 should be set higher.
D. The hello and dead timers are not configured properly.
E. A backup designated router needs to be added to the network.
F. The OSPF process ID numbers must match.
Explanation/Reference:
In OSPF, the hello and dead intervals must match and here we can see the hello interval is set to 5 on R1 and 10 on R2. The dead interval is also set to 20 on R1 but it is 40 on R2.
169. In which circumstance are multiple copies of the same unicast frame likely to be transmitted in a switched LAN?
A. during high traffic periods
B. after broken links are re-established
C. when upper-layer protocols require high reliability
D. in an improperly implemented redundant topology
E. when a dual ring topology is in use
Explanation/Reference:
If we connect two switches via 2 or more links and do not enable STP on these switches then a loop (which creates multiple copies of the same unicast frame) will occur. It is an example of an improperly implemented redundant topology.
170. VLAN 3 is not yet configured on your switch. What happens if you set the switchport access vlan 3
command in interface configuration mode?
A. The command is rejected.
B. The port turns amber.
C. The command is accepted and the respective VLAN is added to vlan.dat.
D. The command is accepted and you must configure the VLAN manually.
Explanation/Reference:
The “switchport access vlan 3” will put that interface as belonging to VLAN 3 while also updated the VLAN database automatically to include VLAN 3.
171. A network administrator is troubleshooting an EIGRP problem on a router and needs to confirm the IP addresses of the devices with which the router has established adjacency. The retransmit interval and the queue counts for the adjacent routers also need to be checked. What command will display the required information?
A. Router# show ip eigrp adjacency
B. Router# show ip eigrp topology
C. Router# show ip eigrp interfaces
D. Router# show ip eigrp neighbors
Explanation/Reference:
Below is an example of the show ip eigrp neighbors command. The retransmit interval (Smooth Round Trip Timer – SRTT) and the queue counts (Q count, which shows the number of queued EIGRP packets) for the adjacent routers are listed:
172. Refer to the graphic. R1 is unable to establish an OSPF neighbor relationship with R3. What are possible reasons for this problem? (Choose two.)
A. All of the routers need to be configured for backbone Area 1.
B. R1 and R2 are the DR and BDR, so OSPF will not establish neighbor adjacency with R3.
C. A static route has been configured from R1 to R3 and prevents the neighbor adjacency from being
established.
D. The hello and dead interval timers are not set to the same values on R1 and R3.
E. EIGRP is also configured on these routers with a lower administrative distance.
F. R1 and R3 are configured in different areas.
Explanation/Reference:
This question is to examine the conditions for OSPF to create neighborhood. So as to make the two routers become neighbors, each router must be matched with the following items: The area ID and its types; Hello and failure time interval timer; OSPF Password (Optional);
173. Refer to the exhibit. The network shown in the diagram is experiencing connectivity problems. Which of the following will correct the problems? (Choose two.)
A. Configure the gateway on Host A as 10.1.1.1.
B. Configure the gateway on Host B as 10.1.2.254.
C. Configure the IP address of Host A as 10.1.2.2.
D. Configure the IP address of Host B as 10.1.2.2.
E. Configure the masks on both hosts to be 255.255.255.224.
F. Configure the masks on both hosts to be 255.255.255.240.
Explanation/Reference:
The switch 1 is configured with two VLANs: VLAN1 and VLAN2. The IP information of member Host A in
VLAN1 is as follows:
Address : 10.1.1.126
Mask : 255.255.255.0
Gateway : 10.1.1.254
The IP information of member Host B in VLAN2 is as follows:
Address : 10.1.1.12
Mask : 255.255.255.0
Gateway : 10.1.1.254
The configuration of sub-interface on router 2 is as follows:
Fa0/0.1 — 10.1.1.254/24 VLAN1
Fa0/0.2 — 10.1.2.254/24 VLAN2
It is obvious that the configurations of the gateways of members in VLAN2 and the associated network segments are wrong. The layer3 addressing information of Host B should be modified as follows:
Address : 10.1.2.X
Mask : 255.255.255.0
174. Refer to the exhibit. A problem with network connectivity has been observed. It is suspected that the cable connected to switch port Fa0/9 on Switch1 is disconnected. What would be an effect of this cable being disconnected?
A. Host B would not be able to access the server in VLAN9 until the cable is reconnected.
B. Communication between VLAN3 and the other VLANs would be disabled.
C. The transfer of files from Host B to the server in VLAN9 would be significantly slower.
D. For less than a minute, Host B would not be able to access the server in VLAN9. Then normal network function would resume.
Explanation/Reference:
Spanning-Tree Protocol (STP) is a Layer 2 protocol that utilizes a special-purpose algorithm to discover physical loops in a network and effect a logical loop-free topology. STP creates a loop- free tree structure consisting of leaves and branches that span the entire Layer 2 network. The actual mechanics of how bridges communicate and how the STP algorithm works will be discussed at length in the following topics. Note that the terms bridge and switch are used interchangeably when discussing STP. In addition, unless otherwise indicated, connections between switches are assumed to be trunks.
175. Refer to the exhibit. HostA cannot ping HostB. Assuming routing is properly configured, what is the cause of this problem?
A. HostA is not on the same subnet as its default gateway.
B. The address of SwitchA is a subnet address.
C. The Fa0/0 interface on RouterA is on a subnet that can’t be used.
D. The serial interfaces of the routers are not on the same subnet.
E. The Fa0/0 interface on RouterB is using a broadcast address.
Explanation/Reference:
Now let’s find out the range of the networks on serial link:
For the network 192.168.1.62/27:
Increment: 32
Network address: 192.168.1.32
Broadcast address: 192.168.1.63 For the network 192.168.1.65/27:
Increment: 32
Network address: 192.168.1.64
Broadcast address: 192.168.1.95
-> These two IP addresses don’t belong to the same network and they can’t see each other
176. Which port state is introduced by Rapid-PVST?
A. learning
B. listening
C. discarding
D. forwarding
Explanation/Reference:
PVST+ is based on IEEE802.1D Spanning Tree Protocol (STP). But PVST+ has only 3 port states (discarding, learning and forwarding) while STP has 5 port states (blocking, listening, learning, forwardingand disabled). So discarding is a new port state in PVST+.
177. Refer to the exhibit. The two connected ports on the switch are not turning orange or green. What would be the most effective steps to troubleshoot this physical layer problem? (Choose three.)
A. Ensure that the Ethernet encapsulations match on the interconnected router and switch ports.
B. Ensure that cables A and B are straight-through cables.
C. Ensure cable A is plugged into a trunk port.
D. Ensure the switch has power.
E. Reboot all of the devices.
F. Reseat all cables.
Explanation/Reference:
The ports on the switch are not up indicating it is a layer 1 (physical) problem so we should check cable type, power and how they are plugged in.
178. Refer to the exhibit. A network administrator attempts to ping Host2 from Host1 and receives the results that are shown. What is the problem?
A. The link between Host1 and Switch1 is down.
B. TCP/IP is not functioning on Host1
C. The link between Router1 and Router2 is down.
D. The default gateway on Host1 is incorrect.
E. Interface Fa0/0 on Router1 is shutdown.
F. The link between Switch1 and Router1 is down
Explanation/Reference:
Host1 tries to communicate with Host2. The message destination host unreachable from Router1 indicates that the problem occurs when the data is forwarded from Host1 to Host2. According to the topology, we can infer that The link between Router1 and Router2 is down.
179. Refer to the exhibit. Hosts in network 192.168.2.0 are unable to reach hosts in network 192.168.3.0. Based on the output from RouterA, what are two possible reasons for the failure? (Choose two.)
A. The cable that is connected to S0/0 on RouterA is faulty.
B. Interface S0/0 on RouterB is administratively down.
C. Interface S0/0 on RouterA is configured with an incorrect subnet mask.
D. The IP address that is configured on S0/0 of RouterB is not in the correct subnet
E. Interface S0/0 on RouterA is not receiving a clock signal from the CSU/DSU.
F. The encapsulation that is configured on S0/0 of RouterB does not match the encapsulation that is configured on S0/0 of RouterA
Explanation/Reference:
From the output we can see that there is a problem with the Serial 0/0 interface. It is enabled, but the line protocol is down. The could be a result of mismatched encapsulation or the interface not receiving a clock signal from the CSU/DSU.
180. Refer to the exhibit. An administrator pings the default gateway at 10.10.10.1 and sees the output as
shown. At which OSI layer is the problem?
A. data link layer
B. application layer
C. access layer
D. session layer
E. network layer
Explanation/Reference:
The command ping uses ICMP protocol, which is a network layer protocol used to propagate control message between host and router. The command ping is often used to verify the network connectivity, so it works at the network layer.
181. Which statement is correct regarding the operation of DHCP?
A. A DHCP client uses a ping to detect address conflicts.
B. A DHCP server uses a gratuitous ARP to detect DHCP clients.
C. A DHCP client uses a gratuitous ARP to detect a DHCP server.
D. If an address conflict is detected, the address is removed from the pool and an administrator must resolve the conflict.
E. If an address conflict is detected, the address is removed from the pool for an amount of time
configurable by the administrator.
F. If an address conflict is detected, the address is removed from the pool and will not be reused until the server is rebooted.
Explanation/Reference:
An address conflict occurs when two hosts use the same IP address. During address assignment, DHCP checks for conflicts using ping and gratuitous ARP. If a conflict is detected, the address is removed from the pool. The address will not be assigned until the administrator resolves the conflict.
182. Refer to the exhibit. Statements A, B, C, and D of ACL 10 have been entered in the shown order and applied to interface E0 inbound, to prevent all hosts (except those whose addresses are the first and last IP of subnet 172.21.1.128/28) from accessing the network. But as is, the ACL does not restrict anyone from the network. How can the ACL statements be re-arranged so that the system works as intended?
A. ACDB
B. BADC
C. DBAC
D. CDBA
Explanation/Reference:
Routers go line by line through an access list until a match is found and then will not look any further, even if a more specific of better match is found later on in the access list. So, it it best to begin with the most specific entries first, in this cast the two hosts in line C and D. Then, include the subnet (B) and then finally the rest of the traffic (A)
183. The output of the show frame-relay pvc command shows “PVC STATUS = INACTIVE”. What does this mean?
A. The PVC is configured correctly and is operating normally, but no data packets have been detected for
more than five minutes.
B. The PVC is configured correctly, is operating normally, and is no longer actively seeking the address of
the remote router.
C. The PVC is configured correctly, is operating normally, and is waiting for interesting traffic to trigger a
call to the remote router.
D. The PVC is configured correctly on the local switch, but there is a problem on the remote end of the PVC.
E. The PVC is not configured on the local switch.
Explanation/Reference:
The PVC STATUS displays the status of the PVC. The DCE device creates and sends the report to the
DTE devices. There are 4 statuses:
+ ACTIVE: the PVC is operational and can transmit data + INACTIVE: the connection from the local router to the switch is working, but the connection to the remote router is not available + DELETED: the PVC is not present and no LMI information is being received from the Frame Relay switch
+ STATIC: the Local Management Interface (LMI) mechanism on the interface is disabled (by using the “nokeepalive” command). This status is rarely seen so it is ignored in some books.
184. Which command is used to enable CHAP authentication, with PAP as the fallback method, on a serial
interface?
A. Router(config-if)# ppp authentication chap fallback ppp
B. Router(config-if)# ppp authentication chap pap
C. Router(config-if)# authentication ppp chap fallback ppp
D. Router(config-if)# authentication ppp chap pap
Explanation/Reference:
This command tells the router to first use CHAP and then go to PAP if CHAP isn’t available
185. Which protocol is an open standard protocol framework that is commonly used in VPNs, to provide secure
end-to-end communications?
A. RSA
B. L2TP
C. IPsec
D. PPTP
Explanation/Reference:
IPSec is a framework of open standards that provides data confidentiality, data integrity, and data authentication between participating peers at the IP layer. IPSec can be used to protect one or more data flows between IPSec peers.
186. At which layer of the OSI model does PPP perform?
A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 5
Explanation/Reference:
The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP was originally emerged as an encapsulation protocol for transporting IP traffic between two peers. It is a data link layer protocol (layer 2 in the OSI model
187. The command frame-relay map ip 10.121.16.8 102 broadcast was entered on the router. Which of the following statements is true concerning this command?
A. This command should be executed from the global configuration mode.
B. The IP address 10.121.16.8 is the local router port used to forward data. C. 102 is the remote DLCI that will receive the information
D. This command is required for all Frame Relay configurations.
E. The broadcast option allows packets, such as RIP updates, to be forwarded across the PVC.
Explanation/Reference:
Broadcast is added to the configurations of the frame relay, so the PVC supports broadcast, allowing the routing protocol updates that use the broadcast update mechanism to be forwarded across itself.
188. Which two options are valid WAN connectivity methods? (Choose two.)
A. PPP
B. WAP
C. DSL
D. L2TPv3
E. Ethernet
Explanation/Reference:
The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP was originally emerged as an encapsulation protocol for transporting IP traffic
between two peers. It is a data link layer protocol used for WAN connections. DSL is also considered a WAN connection, as it can be used to connect networks, typically when used with VPN technology.
189. Which Layer 2 protocol encapsulation type supports synchronous and asynchronous circuits and has built-in security mechanisms?
A. HDLC
B. PPP
C. X.25
D. Frame Relay
Explanation/Reference:
PPP: Provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. PPP was designed to work with several network layer protocols, including IP. PPP also has built-in security mechanisms, such as Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP).
190. Which encapsulation type is a Frame Relay encapsulation type that is supported by Cisco routers?
A. IETF
B. ANSI Annex D
C. Q9333-A Annex A
D. HDLC
Explanation/Reference:
Cisco supports two Frame Relay encapsulation types: the Cisco encapsulation and the IETF Frame Relay encapsulation, which is in conformance with RFC 1490 and RFC 2427. The former is often used to connect two Cisco routers while the latter is used to connect a Cisco router to a non-Cisco router. You can test with your Cisco router when typing the command Router(configif)# encapsulation frame-relay ? on a WAN link. Below is the output of this command (notice Cisco is the default encapsulation so it is not listed here, just press Enter to use it).
Note: Three LMI options are supported by Cisco routers are ansi, Cisco, and Q933a. They represent the ANSI Annex D, Cisco, and ITU Q933-A (Annex A) LMI types, respectively. HDLC is a WAN protocol same as Frame-Relay and PPP so it is not a Frame Relay encapsulation type
191. RouterA is unable to reach RouterB. Both routers are running IOS version 12.0. After reviewing the
command output and graphic, what is the most likely cause of the problem?
A. incorrect bandwidth configuration
B. incorrect LMI configuration
C. incorrect map statement
D. incorrect IP address
Explanation/Reference:
First we have to say this is an unclear question and it is wrong. The “frame-relay map ip” statement is correct thus none of the four answers above is correct. But we guess there is a typo in the output. Maybe the “ip address 172.16.100.2 255.255.0.0 command should be “ip address 172.16.100.1 255.255.0.0.
192. Refer to the exhibit. What is the meaning of the term dynamic as displayed in the output of the show frame-relay map command shown?
A. The Serial0/0 interface is passing traffic.
B. The DLCI 100 was dynamically allocated by the router.
C. The Serial0/0 interface acquired the IP address of 172.16.3.1 from a DHCP server. D. The DLCI 100 will be dynamically changed as required to adapt to changes in the Frame Relay cloud.
E. The mapping between DLCI 100 and the end station IP address 172.16.3.1 was learned through Inverse ARP.
Explanation/Reference:
Inverse Address Resolution Protocol (Inverse ARP) was developed to provide a mechanism for dynamic DLCI to Layer 3 address maps. Inverse ARP works much the same way Address Resolution Protocol (ARP) works on a LAN. However, with ARP, the device knows the Layer 3 IP address and needs to know the remote data link MAC address. With Inverse ARP, the router knows the Layer 2 address which is the DLCI, but needs to know the remote Layer 3 IP address. When using dynamic address mapping, Inverse ARP requests a next-hop protocol address for each active PVC. Once the requesting router receives an Inverse ARP response, it updates its DLCI-to-Layer 3 address mapping table. Dynamic address mapping is enabled by default for all protocols enabled on a physical interface. If the Frame Relay environment supports LMI autosensing and Inverse ARP, dynamic address mapping takes place automatically. Therefore, no static address mapping is required.
193. A network administrator needs to configure a serial link between the main office and a remote location. The router at the remote office is a non-Cisco router. How should the network administrator configure the serial interface of the main office router to make the connection
A. Main(config)# interface serial 0/0
Main(config-if)# ip address 172.16.1.1 255.255.255.252 Main(config-if)# no shut
B. Main(config)# interface serial 0/0
Main(config-if)# ip address 172.16.1.1 255.255.255.252
Main(config-if)# encapsulation ppp Main(config-if)# no shut
C. Main(config)# interface serial 0/0
Main(config-if)# ip address 172.16.1.1 255.255.255.252
Main(config-if)# encapsulation frame-relay
Main(config-if)# authentication chap
Main(config-if)# no shut
D. Main(config)# interface serial 0/0
Main(config-if)#ip address 172.16.1.1 255.255.255.252
Main(config-if)#encapsulation ietf
Main(config-if)# no shut
Explanation/Reference:
With serial point to point links there are two options for the encapsulation. The default, HDLC, is Cisco proprietary and works only with other Cisco routers. The other option is PPP which is standards based and
supported by all vendors.
194. What are three reasons that an organization with multiple branch offices and roaming users might
implement a Cisco VPN solution instead of point-to-point WAN links? (Choose three.)
A. reduced cost
B. better throughput
C. broadband incompatibility
D. increased security
E. scalability
F. reduced latency
Explanation/Reference:
IPsec offer a number of advantages over point to point WAN links, particularly when multiple locations are involved. These include reduced cost, increased security since all traffic is encrypted, and increased scalability as s single WAN link can be used to connect to all locations in a VPN, where as a point to point link would need to be provisioned to each location.
195. Which two statistics appear in show frame-relay map output? (Choose two.)
A. the number of BECN packets that are received by the router
B. the value of the local DLCI
C. the number of FECN packets that are received by the router
D. the status of the PVC that is configured on the router
E. the IP address of the local router
Explanation/Reference:
Sample “show frame-relay map” output:
R1#sh frame mapSerial0/0 (up): ip 10.4.4.1 dlci 401(0x191,0x6410), dynamic,broadcast,, status defined,
activeSerial0/0 (up): ip 10.4.4.3 dlci 403(0x193,0x6430), dynamic,broadcast,, status defined, activeSerial0/0
(up): ip 10.4.4.4 dlci 401(0x191,0x6410), static,CISCO, status defined, active
196. Users have been complaining that their Frame Relay connection to the corporate site is very slow. The network administrator suspects that the link is overloaded.
Based on the partial output of the Router# show frame relay pvc command shown in the graphic, which
output value indicates to the local router that traffic sent to the corporate site is experiencing congestion?
A. DLCI = 100
B. last time PVC status changed 00:25:40
C. in BECN packets 192
D. in FECN packets 147
E. in DE packets 0
Explanation/Reference:
If device A is sending data to device B across a Frame Relay infrastructure and one of the intermediate
Frame Relay switches encounters congestion, congestion being full buffers, over- subscribed port, overloaded resources, etc, it will set the BECN bit on packets being returned to the sending device and the FECN bit on the packets being sent to the receiving device.
197. Which command allows you to verify the encapsulation type (CISCO or IETF) for a Frame Relay link?
A. show frame-relay lmi
B. show frame-relay map
C. show frame-relay pvc
D. show interfaces serial
Explanation/Reference:
When connecting Cisco devices with non-Cisco devices, you must use IETF4 encapsulation on both devices. Check the encapsulation type on the Cisco device with the show frame-relay map exec command.
198. It has become necessary to configure an existing serial interface to accept a second Frame Relay virtual circuit. Which of the following procedures are required to accomplish this task? (Choose three.)
A. Remove the IP address from the physical interface.
B. Encapsulate the physical interface with multipoint PPP.
C. Create the virtual interfaces with the interface command
D. Configure each subinterface with its own IP address.
E. Disable split horizon to prevent routing loops between the subinterface networks.
F. Configure static Frame Relay map entries for each subinterface network.
Explanation/Reference:
For multiple PVC’s on a single interface, you must use subinterfaces, with each subinterface configured for each PVC. Each subinterface will then have its own IP address, and no IP address will be assigned to the main interface.
199.What occurs on a Frame Relay network when the CIR is exceeded?
A. All TCP traffic is marked discard eligible.
B. All UDP traffic is marked discard eligible and a BECN is sent.
C. All TCP traffic is marked discard eligible and a BECN is sent.
D. All traffic exceeding the CIR is marked discard eligible.
Explanation/Reference:
Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the Frame Relay switch. Frames that are sent in excess of the CIR are marked as discard eligible (DE) which means they can be dropped if the congestion occurs within the Frame Relay network. Note: In the Frame Relayframe format, there is a bit called Discard eligible (DE) bit that is used to identify frames that are first to be dropped when the CIR is exceeded.
200. Which two statements about using the CHAP authentication mechanism in a PPP link are true? (Choose two.)
A. CHAP uses a two-way handshake.
B. CHAP uses a three-way handshake.
C. CHAP authentication periodically occurs after link establishment.
D. CHAP authentication passwords are sent in plaintext.
E. CHAP authentication is performed only upon link establishment.
F. CHAP has no protection from playback attacks.
Explanation/Reference:
CHAP is an authentication scheme used by Point to Point Protocol (PPP) servers to validate the identity of remote clients. CHAP periodically verifies the identity of the client by using a three-way handshake. This happens at the time of establishing the initial link (LCP), and may happen again at any time afterwards. The verification is based on a shared secret (such as the client user’s password).
201. Refer to the exhibit. Which statement describes DLCI 17?
A. DLCI 17 describes the ISDN circuit between R2 and R3.
B. DLCI 17 describes a PVC on R2. It cannot be used on R3 or R1.
C. DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.
D. DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.
Explanation/Reference:
DLCI-Data Link Connection Identifier Bits: The DLCI serves to identify the virtual connection so that the receiving end knows which information connection a frame belongs to. Note that this DLCI has only local significance. Frame Relay is strictly a Layer 2 protocol suite.
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