CCNA 640-802 Ver 22-09-2008 page9
QUESTION 81
While troubleshooting a network connectivity problem, a Certkiller technician observes steady link lights on both the workstation NIC and the switch port to which the workstation is connected. However, when the ping command is issued from the workstation, the output message "Request timed out." is displayed. At which layer of the 7-layer OSI model does the problem most likely exist?
A. The data link layer
B. The application layer
C. The protocol layer
D. The access layer
E. The session layer
F. The network layer
G. None of the above
Answer: F
Explanation:
Network Layer:
The Network layer (also called layer 3) manages device addressing, tracks the location of devices on the network, and determines the best way to move data, which means that the Network layer must transport traffic between devices that aren't locally attached. Routers (layer 3 devices) are specified at the Network layer and provide the routing services within an internetwork. Request Time out, Destination Unreachable etc error comes from Network Layer problem.
QUESTION 82
A host is connected to the Certkiller network as displayed below:
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 that switch has power.
E. Reboot all of the devices.
F. Reseat all cables.
Answer: B, D, F
Explanation:
Straight-through cables are used to connect hosts to a switch (or hub) and routers to a switch (or hub). See the table below:
Incorrect Answers:
A: This would mean that there was a layer 2 issue, not layer 1. If the problem was related to the encapsulation, the lights on the switch would indicate layer 1 activity.
C: A trunk port is not required, and again if this was the problem the link lights on the
switch would be on.
E: This should only be used as a last resort, as this will affect all users on the switch.
QUESTION 83
Which line from the output of the show ip interface command indicates that there is a Layer 1 problem?
A. Serial0/1 is up, line protocol is down
B. Serial0/1 is down, line protocol is down
C. Serial0/1 is up, line protocol is up
D. Serial0/1 is administratively down, line protocol is down
E. None of the above
Answer: B
Explanation:
When the physical interface itself is down, then the problem is related to layer 1. When it is up, but the line protocol is down, then the problem is related to layer 2.
QUESTION 84
At which layer of the OSI model does the protocol that provides the information displayed by the "show cdp neighbors" command operate?
A. Transport
B. Physical
C. Application
D. Data link
E. Network
Answer: D
Explanation:
CDP is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco-manufactured devices (routers, bridges, access servers, and switches) and allows network management applications to discover Cisco devices that are neighbors of already known devices. With CDP, network management applications can learn the device type and the Simple Network Management Protocol (SNMP) agent address of neighboring devices running lower-layer, transparent protocols.
QUESTION 85
Which three of the protocols below belong to the application layer? (Select three answer choices)
A. ARP
B. HTTPS
C. SMTP
D. CDP
E. TFTP
F. ICMP
Answer: B, C, E
Explanation:
The application layer is the highest OSI layer, and protocols at this layer are end-user oriented. HTTPS so people can get information on the internet, SMTP so people can manage networks, and TFTP so people can download files.
Incorrect Answers:
A, D, F. ARP, CDP, ICMP are protocols that equipment like routers and switches use to communicate with themselves, and belong to lower levels on the model.
QUESTION 86
Exhibit:
A Cisco router and a Catalyst switch are connected as shown. The Certkiller network administrator is working on a computer that is connected to the management console of the switch. In order to configure the default gateway for the switch, the administrator needs to learn the IP address of the attached router interface. Which IOS command will provide this information in the absence of Layer 3 connectivity?
A. ping router_ip_address
B. show ip rarp
C. ping switch_ip_address
D. show cdp neighbors detail
E. show dhcp-config
F. show ip neighbors
G. None of the above
Answer: D
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. The following is sample output for the show cdp neighbors detail command.
router#show cdp neighbors detail
Device ID: lab-7206
Entry address(es):
IP address: 172.19.169.83
Platform: cisco 7206VXR, Capabilities: Router
Interface: Ethernet0, Port ID (outgoing port): FastEthernet0/0/0 Holdtime : 123 sec
Version :
Cisco Internetwork Operating System Software
IOS (tm) 5800 Software (C5800-P4-M), Version 12.1(2) Copyright (c) 1986-2002 by Cisco Systems, Inc.
advertisement version: 2
Duplex: half
QUESTION 87
You want to upgrade the Certkiller LAN so that all ports operate in full duplex mode. Which statement is true about full-duplex Ethernet when comparing to half-duplex Ethernet?
A. Full-duplex Ethernet consists of a shared cable segment. Half-duplex provides a point-to-point link
B. Full-duplex Ethernet uses two wires to send and receive. Half-duplex Ethernet uses one wire to send and receive
C. Full-duplex Ethernet can provide higher throughput than can half-duplex Ethernet of the same bandwidth
D. Full-duplex Ethernet uses a loopback circuit to detect collisions. Half-duplex Ethernet uses a jam signal
E. None of the above
Answer: C
Explanation:
Full-duplex Ethernet uses two pairs of wires instead of one wire pair like half duplex. And full duplex uses a point-to-point connection between the transmitter of the transmitting device and the receiver of the receiving device. This means that with full-duplex data transfer, you get a faster data transfer compared to half duplex.
QUESTION 88
What are two characteristics of "store and forward" switching? (Select two answer choices)
A. Latency fluctuates regardless of frame size.
B. The switch receives the complete frame before beginning to forward it.
C. Latency through the switch varies with frame length.
D. The switch checks the destination address upon receipt of headers.
Answer: B, C
Explanation:
With store-and-forward, the entire frame is received by the switch before the first bit of the frame is forwarded. As soon as the incoming switch port receives enough of the frame to see the destination MAC address, the forwarding decision is made and the frame is transmitted out the appropriate outgoing port to the destination device. So, each frame might experience slightly less latency. Store and forward switching may add latency when compared to other switching methods such as cut through, but it can reduce the amount of errors that become forwarded through a network.
Incorrect Answers:
A. The amount of latency that is introduced with this method of switching is dependent on the size of the frame, as the switch must wait to receive the entire frame before sending it.
D. The switch must wait for the entire frame before forwarding it on, and not just the headers.
QUESTION 89
Split horizon has been enabled within the Certkiller routed network. Which one of the following statements best explains the split horizon rule?
A. Only routers can split boundaries (horizons) between networks in separate AS numbers.
B. Each AS must keep routing tables converged to prevent dead routes from being advertised across boundaries.
C. Once a route is received on an interface, advertise that route as unreachable back out the same interface.
D. Information about a route should never be sent back in the direction from which the original update came.
E. None of the above
Answer: D
Explanation:
The split horizon rule states:
* Never advertise a route out of the interface through which you learned it. For instance, in Figure 4a below, if Router One is connected to Routers Two and Three through a single multipoint interface (such as Frame Relay), and Router One learned about Network A from Router Two, it will not advertise the route to Network A back out the same interface to Router Three. Router one assumes that Router Three would learn about Network A directly from Router Two.
Incorrect Answers:
A: There is no such requirement
B: Distance vector protocols updates routing table at regular intervals instead of Topology changes
C: This is the definition of the poison reverse rule, not the split horizon rule.
Reference: Wendell Odom. CISCO CCNA Certification Guide (2000 Press) Page 369.
QUESTION 90
Which of the following commands would be applied to a WAN interface, but not on LAN Interface? (Choose all that apply)
A. IP address
B. encapsulation PPP
C. no shutdown
D. authentication CHAP
E. Speed
F. None of the above
Answer: B, D
Explanation:
PPP encapsulation can be used in ISDN interfaces, Asynchronous serial interfaces, and point to point serial WAN connections. PPP is not an option for LAN interfaces. CHAP authentication is a PPP 3 way authentication method. CHAP authentication can only be used on PPP encapsulated interfaces and is not a LAN interface configuration option.
Incorrect Answers:
A, C. This command can be applied to both LAN and WAN interface types.
E. The speed command is used on LAN interfaces, and is not used on WAN interface types.
While troubleshooting a network connectivity problem, a Certkiller technician observes steady link lights on both the workstation NIC and the switch port to which the workstation is connected. However, when the ping command is issued from the workstation, the output message "Request timed out." is displayed. At which layer of the 7-layer OSI model does the problem most likely exist?
A. The data link layer
B. The application layer
C. The protocol layer
D. The access layer
E. The session layer
F. The network layer
G. None of the above
Answer: F
Explanation:
Network Layer:
The Network layer (also called layer 3) manages device addressing, tracks the location of devices on the network, and determines the best way to move data, which means that the Network layer must transport traffic between devices that aren't locally attached. Routers (layer 3 devices) are specified at the Network layer and provide the routing services within an internetwork. Request Time out, Destination Unreachable etc error comes from Network Layer problem.
QUESTION 82
A host is connected to the Certkiller network as displayed below:
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 that switch has power.
E. Reboot all of the devices.
F. Reseat all cables.
Answer: B, D, F
Explanation:
Straight-through cables are used to connect hosts to a switch (or hub) and routers to a switch (or hub). See the table below:
Incorrect Answers:
A: This would mean that there was a layer 2 issue, not layer 1. If the problem was related to the encapsulation, the lights on the switch would indicate layer 1 activity.
C: A trunk port is not required, and again if this was the problem the link lights on the
switch would be on.
E: This should only be used as a last resort, as this will affect all users on the switch.
QUESTION 83
Which line from the output of the show ip interface command indicates that there is a Layer 1 problem?
A. Serial0/1 is up, line protocol is down
B. Serial0/1 is down, line protocol is down
C. Serial0/1 is up, line protocol is up
D. Serial0/1 is administratively down, line protocol is down
E. None of the above
Answer: B
Explanation:
When the physical interface itself is down, then the problem is related to layer 1. When it is up, but the line protocol is down, then the problem is related to layer 2.
QUESTION 84
At which layer of the OSI model does the protocol that provides the information displayed by the "show cdp neighbors" command operate?
A. Transport
B. Physical
C. Application
D. Data link
E. Network
Answer: D
Explanation:
CDP is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco-manufactured devices (routers, bridges, access servers, and switches) and allows network management applications to discover Cisco devices that are neighbors of already known devices. With CDP, network management applications can learn the device type and the Simple Network Management Protocol (SNMP) agent address of neighboring devices running lower-layer, transparent protocols.
QUESTION 85
Which three of the protocols below belong to the application layer? (Select three answer choices)
A. ARP
B. HTTPS
C. SMTP
D. CDP
E. TFTP
F. ICMP
Answer: B, C, E
Explanation:
The application layer is the highest OSI layer, and protocols at this layer are end-user oriented. HTTPS so people can get information on the internet, SMTP so people can manage networks, and TFTP so people can download files.
Incorrect Answers:
A, D, F. ARP, CDP, ICMP are protocols that equipment like routers and switches use to communicate with themselves, and belong to lower levels on the model.
QUESTION 86
Exhibit:
A Cisco router and a Catalyst switch are connected as shown. The Certkiller network administrator is working on a computer that is connected to the management console of the switch. In order to configure the default gateway for the switch, the administrator needs to learn the IP address of the attached router interface. Which IOS command will provide this information in the absence of Layer 3 connectivity?
A. ping router_ip_address
B. show ip rarp
C. ping switch_ip_address
D. show cdp neighbors detail
E. show dhcp-config
F. show ip neighbors
G. None of the above
Answer: D
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. The following is sample output for the show cdp neighbors detail command.
router#show cdp neighbors detail
Device ID: lab-7206
Entry address(es):
IP address: 172.19.169.83
Platform: cisco 7206VXR, Capabilities: Router
Interface: Ethernet0, Port ID (outgoing port): FastEthernet0/0/0 Holdtime : 123 sec
Version :
Cisco Internetwork Operating System Software
IOS (tm) 5800 Software (C5800-P4-M), Version 12.1(2) Copyright (c) 1986-2002 by Cisco Systems, Inc.
advertisement version: 2
Duplex: half
QUESTION 87
You want to upgrade the Certkiller LAN so that all ports operate in full duplex mode. Which statement is true about full-duplex Ethernet when comparing to half-duplex Ethernet?
A. Full-duplex Ethernet consists of a shared cable segment. Half-duplex provides a point-to-point link
B. Full-duplex Ethernet uses two wires to send and receive. Half-duplex Ethernet uses one wire to send and receive
C. Full-duplex Ethernet can provide higher throughput than can half-duplex Ethernet of the same bandwidth
D. Full-duplex Ethernet uses a loopback circuit to detect collisions. Half-duplex Ethernet uses a jam signal
E. None of the above
Answer: C
Explanation:
Full-duplex Ethernet uses two pairs of wires instead of one wire pair like half duplex. And full duplex uses a point-to-point connection between the transmitter of the transmitting device and the receiver of the receiving device. This means that with full-duplex data transfer, you get a faster data transfer compared to half duplex.
QUESTION 88
What are two characteristics of "store and forward" switching? (Select two answer choices)
A. Latency fluctuates regardless of frame size.
B. The switch receives the complete frame before beginning to forward it.
C. Latency through the switch varies with frame length.
D. The switch checks the destination address upon receipt of headers.
Answer: B, C
Explanation:
With store-and-forward, the entire frame is received by the switch before the first bit of the frame is forwarded. As soon as the incoming switch port receives enough of the frame to see the destination MAC address, the forwarding decision is made and the frame is transmitted out the appropriate outgoing port to the destination device. So, each frame might experience slightly less latency. Store and forward switching may add latency when compared to other switching methods such as cut through, but it can reduce the amount of errors that become forwarded through a network.
Incorrect Answers:
A. The amount of latency that is introduced with this method of switching is dependent on the size of the frame, as the switch must wait to receive the entire frame before sending it.
D. The switch must wait for the entire frame before forwarding it on, and not just the headers.
QUESTION 89
Split horizon has been enabled within the Certkiller routed network. Which one of the following statements best explains the split horizon rule?
A. Only routers can split boundaries (horizons) between networks in separate AS numbers.
B. Each AS must keep routing tables converged to prevent dead routes from being advertised across boundaries.
C. Once a route is received on an interface, advertise that route as unreachable back out the same interface.
D. Information about a route should never be sent back in the direction from which the original update came.
E. None of the above
Answer: D
Explanation:
The split horizon rule states:
* Never advertise a route out of the interface through which you learned it. For instance, in Figure 4a below, if Router One is connected to Routers Two and Three through a single multipoint interface (such as Frame Relay), and Router One learned about Network A from Router Two, it will not advertise the route to Network A back out the same interface to Router Three. Router one assumes that Router Three would learn about Network A directly from Router Two.
Incorrect Answers:
A: There is no such requirement
B: Distance vector protocols updates routing table at regular intervals instead of Topology changes
C: This is the definition of the poison reverse rule, not the split horizon rule.
Reference: Wendell Odom. CISCO CCNA Certification Guide (2000 Press) Page 369.
QUESTION 90
Which of the following commands would be applied to a WAN interface, but not on LAN Interface? (Choose all that apply)
A. IP address
B. encapsulation PPP
C. no shutdown
D. authentication CHAP
E. Speed
F. None of the above
Answer: B, D
Explanation:
PPP encapsulation can be used in ISDN interfaces, Asynchronous serial interfaces, and point to point serial WAN connections. PPP is not an option for LAN interfaces. CHAP authentication is a PPP 3 way authentication method. CHAP authentication can only be used on PPP encapsulated interfaces and is not a LAN interface configuration option.
Incorrect Answers:
A, C. This command can be applied to both LAN and WAN interface types.
E. The speed command is used on LAN interfaces, and is not used on WAN interface types.
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