CCNA 640-802 Ver 22-09-2008 page8
QUESTION 71
Part of the Certkiller network is shown below:
In this network segment, host Certkiller A sends data to Host Certkiller B. As packets travel from host Certkiller A to host Certkiller B, which three devices will use the destination MAC address of the packet to determine a forwarding path? (Choose three)
A. Hub Certkiller 0
B. Switch Certkiller 1
C. Router Certkiller 5
D. Router Certkiller 4
E. Switch Certkiller 2
F. Switch Certkiller 3
Answer: B, E, F
Explanation:
Switches use the destination MAC address information for forwarding traffic, while routers use the destination IP address information. Local Area Networks employ Layer 2 Switches and Bridges to forward and filter network traffic. Switches and Bridges operate at the Data Link Layer of the Open System Interconnect Model (OSI). Since Switches and Bridges operate at the Layer 2 they operate more intelligently than hubs, which work at Layer 1 (Physical Layer) of the OSI. Because the switches and bridges are able to listen to the traffic on the wire to examine the source and destination MAC address. Being able to listen to the traffic also allows the switches and bridges to compile a MAC address table to better filter and forward network traffic. To accomplish the above functions switches and bridges carry out the following tasks:
1. MAC address learning by a switch or a bridge is accomplished by the same method. The switch or bridge listens to each device connected to each of its ports and scan the incoming frame for the source MAC address. This creates a MAC address to port map that is cataloged in the switches/bridge MAC database. Another name for the MAC address table is content addressable memory or CAM table.
2. When a switch or bridge is listening o the network traffic, it receives each frame and compares it to the MAC address table. By checking the MAC table the switch/ bridge are able o determine which port the frame came in on. If the frame is on the MAC table the frame is filtered or transmitted on only that port. If the switch determines that the frame is not on the MAC table, the frame is forwarded out to all ports except the incoming port.
QUESTION 72
Exhibit:
You work as a network technician at Certkiller .com. Please study the exhibit carefully. Host Certkiller A is communicating with the server. What will be the source MAC address of the frames received by Host Certkiller A from the Certkiller B server?
A. The MAC address of Certkiller 2 router interface e1
B. The MAC address of Certkiller 2 router interface e0
C. The MAC address of the Certkiller B server network interface
D. The MAC address of host Certkiller A
E. None of the above
Answer: B
Explanation:
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:
1. 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.
2. 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.
3. 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.)
4. 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.
Figure 5 shows the contents of a packet before and after it has been forwarded by a router. Figure 5 also shows the contents of the router's routing tables.
Figure 5: Routers forward packets based on the network address.
QUESTION 73
The Certkiller network is displayed in the diagram shown below:
The Certkiller network consists of a small office with twenty-five employees that has one connection to the Internet through the CK1 router. What routing configurations are recommended on the CK1 and ISP routers?
A. BGP on both the routers.
B. RIP on both the routers.
C. Default routes on both routers.
D. BGP on the ISP router and a static route on CK1 .
E. A default route on CK1 and a static route on the ISP router.
F. None of the above
Answer: E
Explanation:
Since private network use RFC 1918 IP address ranges internally, and because of security reasons, it is generally not possible to use an interior routing protocol with the ISP. This eliminates choice B. When connecting to an ISP, usually only BGP or static routes are supported. In this case, since there is only one connection to the Internet, BGP is not needed so choices A and D can be eliminated. A static default route would be needed on router CK1 to route to the Internet. In turn, the ISP only needs a specific static route to reach the LAN of the Certkiller network.
Incorrect Answers:
A. D: BGP is not needed on networks that contain only a single link to the Internet.
B. Interior routing protocols are generally not supported with an ISP.
C. A default route on the ISP router would send all of their customers Internet traffic to the Certkiller network, and not the Internet.
QUESTION 74
A new point to point circuit is installed, connecting Certkiller 1 to Certkiller 2 as shown below:
Users at Certkiller 1 wish to utilize the existing Internet connection at Certkiller 2. To do this, a gateway of last resort needs to be set. What is the command to do this?
A. Certkiller 1(config)# ip route 172.16.4.2 0.0.0.0 0.0.0.0
B. Certkiller 1(config)# ip route 0.0.0.0 0.0.0.0 S1
C. Certkiller 1(config)# ip route 172.16.4.1 0.0.0.0 0.0.0.0
D. Certkiller 1(config)# ip route S0 0.0.0.0 0.0.0.0
E. Certkiller 1(config)# ip route 0.0.0.0 0.0.0.0 172.16.4.2
F. None of the above
Answer: E
Explanation:
Setting the default gateway is done by issuing either the "ip route 0.0.0.0 0.0.0.0 serial 0" or the "ip route 0.0.0.0 0.0.0.0 172.16.4.2" command. The following excerpt provides some additional information:
Incorrect Answers:
A, C. The IP address of the next hop needs to go after the route, not before.
B. This would have been acceptable if the interface specified was S0, not S1.
C. The interface used to forward packets for the route should be placed after the route, not before.
QUESTION 75
The network associate is configuring OSPF on the Core router shown below. All the connections to the branches should be participating in OSPF. The link to the ISP should NOT participate in OSPF and should only be advertised as the default route. What set of commands will properly configure the Core router?
A. Core(config-router)# default-information originate
Core(config-router)# network 10.0.0.0 0.255.255.255 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.010.10.2.14
B. Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.32 0.0.0.31 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.0 10.10.2.14
C. Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.13 0.0.0.242 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.010.10.2.14
D. Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.16 0.0.0.15 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.010.10.2.14
Answer: D
Explanation:
There are two ways to inject a default route into a normal area.
1. If the ASBR already has the default route in its routing table, you can advertise the existing 0.0.0.0/0 into the OSPF domain with the default-information originate router configuration command.
2. If the ASBR doesn't have a default route, you can add the keyword always to the default-information originate command (default-information originate always). This command will advertise a default route into the OSPF domain, regardless of whether it has a route to 0.0.0.0. Another benefit of adding always keyword is that it can add stability to the internetwork. For example, if the ASBR is learning a default route from another routing domain such as RIP and this route is flapping, then without the always keyword, each time the route flaps, the ASBR will send a new Type 5 LSA into the OSPF domain causing some instability inside the OSPF domain. With the always keyword, the ASBR will advertise the default inside the OSPF domain always, and thus the flapping of the default route from the RIP domain will not cause any instability inside the OSPF domain. In the example shown here, only choice D is correct as the wildcard mask correctly specifies the 10.10.2.16 0.0.0.15 networks, which include all IP addresses in the 10.10.2.16-10.10.2.31 range. In this question we were told that the ISP link should NOT be configured for OSPF, making choice A incorrect.
Reference: http://www.cisco.com/warp/public/104/21.html
QUESTION 76
A new Internet T1 is being added to the Certkiller network as shown:
The ISP assigned you the class CIP address 207.134.6.0/30 for this Internet connection. A default route to the Internet should be set up. Which of the following are acceptable ways to configure this on the Gateway router? (Select all that apply)
A. Gateway(config)# ip route 0.0.0.0 0.0.0.0 207.134.6.1.
B. Gateway(config)# router rip
Gateway(config-router)# network 207.134.6.0 default
C. Gateway(config)# ip route 207.134.6.0 255.255.255.0 Serial0/0
D. Gateway(config)# router OSPF
Gateway(config-router)# network 207.134.6.0
E. Gateway(config)# ip default-network 207.134.6.0
Answer: A, E
Explanation:
This question only involves the configuration of the gateway router to the ISP, nothing else. You have two choices to accomplish this: the command "ip route" or the command "ip default-network". Both of these methods will configure a default route to the ISP as desired.
Incorrect Answers:
B, D: RIP and OSPF are interior routing protocols. The T1 Internet connection that is being set up here is between two different Autonomous Systems. The only routing protocol that could be potentially used is BGP, but that is not an option.
C: This command will only set up a static route to the 207.134.6.0/24 network. We wish to set up a static default route.
QUESTION 77
Router Certkiller 2 is connected to an ISP as shown below:
In the ISP link to the WAN shown above, you must complete the connection between the Certkiller 2 router to the service provider. To accomplish this task, which two devices could be installed at the Certkiller site to provide a connection through the local loop to the CO of the provider? (Choose two)
A. Multiplexer
B. WAN switch
C. ATM switch
D. CSU/DSU
E. PVC
F. Modem
G. LMI
Answer: D, F
QUESTION 78
Part of the Certkiller network is shown below:
Study the exhibit shown above. A problem with network connectivity has been observed. It is suspected that the cable connected to switch port Fa0/9 on Switch Certkiller 1 is disconnected. What would be an effect of this cable being disconnected?
A. Communication between VLAN3 and the other VLANs would be disabled
B. Host Certkiller B would not be able to access the server in VLAN9 until the cable is reconnected
C. For less than a minute, Host Certkiller B would not be able to access the server in VLAN9. Then normal network function would resume
D. The transfer of files from Host Certkiller B to the server in VLAN9 would be significantly slower
E. None of the above
Answer: C
Explanation:
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. STP keeps the port either in block or in forward states, when forward port disconnect then within the less then a minute blocked port comes into forward state so packets starts to go through new forward port. The Spanning Tree Protocol (STP) would identify the best path as well as alternate path to reach in proper destination. In a redundant link, if the primary link fails then the secondary links will automatically start after few minutes. If port Fa0/9 became disconnected, then the packets would be re-routed automatically using the Certkiller A- Certkiller 2- Certkiller 3 path.
QUESTION 79
You are logged into a router and wish to view the layer 3 information about your neighboring Cisco routers. What IOS command gives layer 3 information for of the directly connected router interfaces?
A. show ip links
B. show cdp neighbor
C. show cdp neighbor detail
D. show ip clients
E. show ip route
F. None of the above
Answer: C
Explanation:
To display detailed information about neighboring devices discovered using Cisco Discovery Protocol (CDP), use the show cdp neighbors privileged EXEC command. Detail - (Optional) Displays detailed information about a neighbor (or neighbors) including network address, enabled protocols, hold time, and software version.
Incorrect Answers:
A, D. These are invalid commands.
B. The "show cdp neighbor" command, without the "detail" keyword will not display the additional layer 3 protocol information.
E. This will show all routes from all other routers within the domain. We wish to see information from just the direct interface neighbors.
QUESTION 80
A Certkiller technician is troubleshooting connectivity problems between two routers that are directly connected through the serial line. The technician notices that the serial line is up but cannot see any neighbors displayed in the output of the show cdp neighbors command. In which OSI layer is the problem most likely occurring?
A. Physical
B. Data link
C. Network layer
D. Transport layer
E. Application layer
Answer: B
Explanation:
As the question states that serial line is up, it means the problem is not on the Network layer. The administrator cannot see any output by issuing the show cdp neighbors command. It means that CDP is disabled and CDP is a protocol that runs over Layer2 (the data link layer) on all Cisco routers, bridges, access servers, and switches.
In this network segment, host Certkiller A sends data to Host Certkiller B. As packets travel from host Certkiller A to host Certkiller B, which three devices will use the destination MAC address of the packet to determine a forwarding path? (Choose three)
A. Hub Certkiller 0
B. Switch Certkiller 1
C. Router Certkiller 5
D. Router Certkiller 4
E. Switch Certkiller 2
F. Switch Certkiller 3
Answer: B, E, F
Explanation:
Switches use the destination MAC address information for forwarding traffic, while routers use the destination IP address information. Local Area Networks employ Layer 2 Switches and Bridges to forward and filter network traffic. Switches and Bridges operate at the Data Link Layer of the Open System Interconnect Model (OSI). Since Switches and Bridges operate at the Layer 2 they operate more intelligently than hubs, which work at Layer 1 (Physical Layer) of the OSI. Because the switches and bridges are able to listen to the traffic on the wire to examine the source and destination MAC address. Being able to listen to the traffic also allows the switches and bridges to compile a MAC address table to better filter and forward network traffic. To accomplish the above functions switches and bridges carry out the following tasks:
1. MAC address learning by a switch or a bridge is accomplished by the same method. The switch or bridge listens to each device connected to each of its ports and scan the incoming frame for the source MAC address. This creates a MAC address to port map that is cataloged in the switches/bridge MAC database. Another name for the MAC address table is content addressable memory or CAM table.
2. When a switch or bridge is listening o the network traffic, it receives each frame and compares it to the MAC address table. By checking the MAC table the switch/ bridge are able o determine which port the frame came in on. If the frame is on the MAC table the frame is filtered or transmitted on only that port. If the switch determines that the frame is not on the MAC table, the frame is forwarded out to all ports except the incoming port.
QUESTION 72
Exhibit:
You work as a network technician at Certkiller .com. Please study the exhibit carefully. Host Certkiller A is communicating with the server. What will be the source MAC address of the frames received by Host Certkiller A from the Certkiller B server?A. The MAC address of Certkiller 2 router interface e1
B. The MAC address of Certkiller 2 router interface e0
C. The MAC address of the Certkiller B server network interface
D. The MAC address of host Certkiller A
E. None of the above
Answer: B
Explanation:
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:
1. 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.
2. 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.
3. 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.)
4. 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.
Figure 5 shows the contents of a packet before and after it has been forwarded by a router. Figure 5 also shows the contents of the router's routing tables.
Figure 5: Routers forward packets based on the network address.
QUESTION 73
The Certkiller network is displayed in the diagram shown below:
The Certkiller network consists of a small office with twenty-five employees that has one connection to the Internet through the CK1 router. What routing configurations are recommended on the CK1 and ISP routers?
A. BGP on both the routers.
B. RIP on both the routers.
C. Default routes on both routers.
D. BGP on the ISP router and a static route on CK1 .
E. A default route on CK1 and a static route on the ISP router.
F. None of the above
Answer: E
Explanation:
Since private network use RFC 1918 IP address ranges internally, and because of security reasons, it is generally not possible to use an interior routing protocol with the ISP. This eliminates choice B. When connecting to an ISP, usually only BGP or static routes are supported. In this case, since there is only one connection to the Internet, BGP is not needed so choices A and D can be eliminated. A static default route would be needed on router CK1 to route to the Internet. In turn, the ISP only needs a specific static route to reach the LAN of the Certkiller network.
Incorrect Answers:
A. D: BGP is not needed on networks that contain only a single link to the Internet.
B. Interior routing protocols are generally not supported with an ISP.
C. A default route on the ISP router would send all of their customers Internet traffic to the Certkiller network, and not the Internet.
QUESTION 74
A new point to point circuit is installed, connecting Certkiller 1 to Certkiller 2 as shown below:
Users at Certkiller 1 wish to utilize the existing Internet connection at Certkiller 2. To do this, a gateway of last resort needs to be set. What is the command to do this?A. Certkiller 1(config)# ip route 172.16.4.2 0.0.0.0 0.0.0.0
B. Certkiller 1(config)# ip route 0.0.0.0 0.0.0.0 S1
C. Certkiller 1(config)# ip route 172.16.4.1 0.0.0.0 0.0.0.0
D. Certkiller 1(config)# ip route S0 0.0.0.0 0.0.0.0
E. Certkiller 1(config)# ip route 0.0.0.0 0.0.0.0 172.16.4.2
F. None of the above
Answer: E
Explanation:
Setting the default gateway is done by issuing either the "ip route 0.0.0.0 0.0.0.0 serial 0" or the "ip route 0.0.0.0 0.0.0.0 172.16.4.2" command. The following excerpt provides some additional information:
Incorrect Answers:
A, C. The IP address of the next hop needs to go after the route, not before.
B. This would have been acceptable if the interface specified was S0, not S1.
C. The interface used to forward packets for the route should be placed after the route, not before.
QUESTION 75
The network associate is configuring OSPF on the Core router shown below. All the connections to the branches should be participating in OSPF. The link to the ISP should NOT participate in OSPF and should only be advertised as the default route. What set of commands will properly configure the Core router?
A. Core(config-router)# default-information originate
Core(config-router)# network 10.0.0.0 0.255.255.255 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.010.10.2.14
B. Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.32 0.0.0.31 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.0 10.10.2.14
C. Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.13 0.0.0.242 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.010.10.2.14
D. Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.16 0.0.0.15 area 0 Core(config-router)# exit
Core(config)# ip route 0.0.0.00.0.0.010.10.2.14
Answer: D
Explanation:
There are two ways to inject a default route into a normal area.
1. If the ASBR already has the default route in its routing table, you can advertise the existing 0.0.0.0/0 into the OSPF domain with the default-information originate router configuration command.
2. If the ASBR doesn't have a default route, you can add the keyword always to the default-information originate command (default-information originate always). This command will advertise a default route into the OSPF domain, regardless of whether it has a route to 0.0.0.0. Another benefit of adding always keyword is that it can add stability to the internetwork. For example, if the ASBR is learning a default route from another routing domain such as RIP and this route is flapping, then without the always keyword, each time the route flaps, the ASBR will send a new Type 5 LSA into the OSPF domain causing some instability inside the OSPF domain. With the always keyword, the ASBR will advertise the default inside the OSPF domain always, and thus the flapping of the default route from the RIP domain will not cause any instability inside the OSPF domain. In the example shown here, only choice D is correct as the wildcard mask correctly specifies the 10.10.2.16 0.0.0.15 networks, which include all IP addresses in the 10.10.2.16-10.10.2.31 range. In this question we were told that the ISP link should NOT be configured for OSPF, making choice A incorrect.
Reference: http://www.cisco.com/warp/public/104/21.html
QUESTION 76
A new Internet T1 is being added to the Certkiller network as shown:
The ISP assigned you the class CIP address 207.134.6.0/30 for this Internet connection. A default route to the Internet should be set up. Which of the following are acceptable ways to configure this on the Gateway router? (Select all that apply)A. Gateway(config)# ip route 0.0.0.0 0.0.0.0 207.134.6.1.
B. Gateway(config)# router rip
Gateway(config-router)# network 207.134.6.0 default
C. Gateway(config)# ip route 207.134.6.0 255.255.255.0 Serial0/0
D. Gateway(config)# router OSPF
Gateway(config-router)# network 207.134.6.0
E. Gateway(config)# ip default-network 207.134.6.0
Answer: A, E
Explanation:
This question only involves the configuration of the gateway router to the ISP, nothing else. You have two choices to accomplish this: the command "ip route" or the command "ip default-network". Both of these methods will configure a default route to the ISP as desired.
Incorrect Answers:
B, D: RIP and OSPF are interior routing protocols. The T1 Internet connection that is being set up here is between two different Autonomous Systems. The only routing protocol that could be potentially used is BGP, but that is not an option.
C: This command will only set up a static route to the 207.134.6.0/24 network. We wish to set up a static default route.
QUESTION 77
Router Certkiller 2 is connected to an ISP as shown below:
In the ISP link to the WAN shown above, you must complete the connection between the Certkiller 2 router to the service provider. To accomplish this task, which two devices could be installed at the Certkiller site to provide a connection through the local loop to the CO of the provider? (Choose two)
A. Multiplexer
B. WAN switch
C. ATM switch
D. CSU/DSU
E. PVC
F. Modem
G. LMI
Answer: D, F
QUESTION 78
Part of the Certkiller network is shown below:
Study the exhibit shown above. A problem with network connectivity has been observed. It is suspected that the cable connected to switch port Fa0/9 on Switch Certkiller 1 is disconnected. What would be an effect of this cable being disconnected?A. Communication between VLAN3 and the other VLANs would be disabled
B. Host Certkiller B would not be able to access the server in VLAN9 until the cable is reconnected
C. For less than a minute, Host Certkiller B would not be able to access the server in VLAN9. Then normal network function would resume
D. The transfer of files from Host Certkiller B to the server in VLAN9 would be significantly slower
E. None of the above
Answer: C
Explanation:
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. STP keeps the port either in block or in forward states, when forward port disconnect then within the less then a minute blocked port comes into forward state so packets starts to go through new forward port. The Spanning Tree Protocol (STP) would identify the best path as well as alternate path to reach in proper destination. In a redundant link, if the primary link fails then the secondary links will automatically start after few minutes. If port Fa0/9 became disconnected, then the packets would be re-routed automatically using the Certkiller A- Certkiller 2- Certkiller 3 path.
QUESTION 79
You are logged into a router and wish to view the layer 3 information about your neighboring Cisco routers. What IOS command gives layer 3 information for of the directly connected router interfaces?
A. show ip links
B. show cdp neighbor
C. show cdp neighbor detail
D. show ip clients
E. show ip route
F. None of the above
Answer: C
Explanation:
To display detailed information about neighboring devices discovered using Cisco Discovery Protocol (CDP), use the show cdp neighbors privileged EXEC command. Detail - (Optional) Displays detailed information about a neighbor (or neighbors) including network address, enabled protocols, hold time, and software version.
Incorrect Answers:
A, D. These are invalid commands.
B. The "show cdp neighbor" command, without the "detail" keyword will not display the additional layer 3 protocol information.
E. This will show all routes from all other routers within the domain. We wish to see information from just the direct interface neighbors.
QUESTION 80
A Certkiller technician is troubleshooting connectivity problems between two routers that are directly connected through the serial line. The technician notices that the serial line is up but cannot see any neighbors displayed in the output of the show cdp neighbors command. In which OSI layer is the problem most likely occurring?
A. Physical
B. Data link
C. Network layer
D. Transport layer
E. Application layer
Answer: B
Explanation:
As the question states that serial line is up, it means the problem is not on the Network layer. The administrator cannot see any output by issuing the show cdp neighbors command. It means that CDP is disabled and CDP is a protocol that runs over Layer2 (the data link layer) on all Cisco routers, bridges, access servers, and switches.
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