CCNA 640-802 Ver 22-09-2008 page7
QUESTION 61
Which IOS user EXEC command will allow a network technician to determine which router in the path to an unreachable network host should be examined more closely for the cause of the network failure?
A. Certkiller B> telnet
B. Certkiller B > ping
C. Certkiller B > trace
D. Certkiller B > show ip route
E. Certkiller B > show interface
F. Certkiller B > show cdp neighbors
Answer: C
Explanation:
This can perform the trace command. It sends the ping packets to each of the routers on the way to the receiver. The router which doesn't respond will be a potential failure place in this network.
QUESTION 62
A Certkiller office's network topology is shown in the diagram below:
Host Certkiller A needs to communications with the e-mail server shown above. What address will be placed on the destination address field of the frame when it leaves host Certkiller A?
A. The MAC address of Certkiller A
B. The MAC address of switch Certkiller 1
C. The MAC address of the E0 interface of the Certkiller 3 router.
D. The MAC address of the E1 interface of the Certkiller 3 router.
E. The MAC address of switch Certkiller 2
F. The MAC address of the email server
Answer: C
Explanation:
If the destination host is in the remote segment than the router will change the MAC address of the source to its own. The inverse ARP protocol is by default on. Remember that IP address is not changed after forwarding. The MAC address is changed after crossing each broadcast domain.
QUESTION 63
The Certkiller network topology is shown below:
You work as a network engineer at Certkiller .com. The topology of the Certkiller .com network is displayed in the exhibit. Host Certkiller 1 has established a connection with the HTTP server attached to interface E0 of the Certkiller B router. Which of the following statements describe the information contained in protocol data units sent from host Certkiller 1 to this server? (Select three)
A. The destination port number in a segment header will have a value of 80.
B. The destination port number in a segment header will have a unique value greater than or equal to 1023.
C. The destination address of a frame will be the MAC address of the HTTP server interface.
D. The destination address of a frame will be the MAC address of the E0 interface of the Certkiller A router.
E. The destination IP address of a packet will be the IP address of the E0 interface of the Certkiller A router.
F. The destination address of a packet will be the IP address of the HTTP-Server
Answer: A, D, F
Explanation:
HTTP uses TCP port 80, making choice A correct. The source port will be chosen randomly, but not the destination TCP port. The destination IP address will be left unchanged, and since HTTP server is on a remote network, the destination MAC address will be the MAC address of the default gateway ( E0 on Certkiller A).
QUESTION 64
The Certkiller network is shown belod:
In this network, host Certkiller 1 is able to send data to Host Certkiller 2. How will Router Certkiller D handle the data frame received from Host Certkiller 1? (Choose three)
A. Router Certkiller D will strip off the source MAC address and replace it with the MAC address on the forwarding Fast Ethernet interface
B. Router Certkiller D will strip off the source IP address and replace it with the IP address on the forwarding Fast Ethernet interface
C. Router Certkiller D will strip off the destination MAC address and replace it with the MAC address of Host Certkiller 2
D. Router Certkiller D will strip off the destination IP address and replace it with the IP address of Host B
E. Router Certkiller D will forward the data frame out interface Fast Ethernet0/1
F. Router Certkiller D will forward the data frame out interface FastEthernet0/2
Answer: A, C, F
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 65
Two Certkiller hosts are shown below:
Refer to the exhibit above. Host A is communicating with host B. How will the data be addressed when it leaves host A?
A. Source MAC=000A.8A47.E612
Destination MAC=000B.DC04.12F4
Source IP=192.168.23.4
Destination IP=192.168.23.1
B. Source MAC=000A.8A47.E612
Destination MAC=0010.7BE7.FAEF
Source IP=192.168.23.4
Destination IP=192.168.127.7
C. Source MAC=000A.8A47.E612
Destination MAC=000B.DC04.12F4
Source IP=192.168.23.4
Destination IP=192.168.127.7
D. Source MAC=000A.8A47.E612
Destination MAC=0010.7BE7.FAEF
Source IP=192.168.23.4
Destination IP=192.168.23.1
E. None of the above
Answer: B
Explanation:
When packets leave from the host, the packets contains the source MAC and IP of the host address. The source and destination IP address will not change (if it did, the router devices would not know where to send the data). Because the host knows that the destination is on another subnet, it will forward the packet to the default gateway device, so the destination MAC address will be of the default gateway, which is the LAN interface of router Certkiller 1.
QUESTION 66
Exhibit:
Please study the exhibit above carefully. If host Certkiller A sends an IP packet to host Certkiller B, what will the OSI Layer 3 source address be in the packet when it reaches host B?
A. B2:B2:B2:B2:B2:B2
B. A1:A1:A1:A1:A1:A1
C. 10.168.10.99
D. 10.168.11.65
E. C3:C3:C3:C3:C3:C3
F. 10.168.11.88
G. None of the above
Answer: C
Explanation:
When packets transfer from one host to another across a routed segment, the source IP address always remains the same source IP address, and the physical (MAC) address will be the existing router's interface address. Similarly, the destination IP address always remains the same and the destination physical (MAC) address is the destination router's interface address.
QUESTION 67
Exhibit:
Please study the exhibit carefully. If host Certkiller A sends an IP packet to host Certkiller B, what will the source physical (MAC) address be in the frame when it reaches host Certkiller B?
A. A1:A1:A1:A1:A1:A1
B. D4:D4:D4:D4:D4:D4
C. B2:B2:B2:B2:B2:B2
D. 10.168.11.88
E. 10.168.10.99
F. C3:C3:C3:C3:C3:C3
Answer: F
Explanation:
When packets transfer from one host to another across a routed segment, the source IP address always remains the same source IP address, and the source physical (MAC) address will be the existing router's interface address. Similarly, the destination IP address always remains the same and the destination physical (MAC) address is the destination router's interface address.
QUESTION 68
In the network below, host Certkiller A is transferring a file to the FTP server. Point A represents the frame as it goes toward the Certkiller 1 router. What will the Layer 2 destination address be at this point?
A. 192.168.7.17
B. abcd.1123.0045
C. aabb.555.2222
D. 192.168.1.1
E. abcd.2246.0035
Answer: E
Explanation:
For packets destined to a host on another IP network, the destination MAC address will be the LAN interface of the router. Since the FTP server lies on a different network, the host will know to send the frame to it's default gateway, which is Certkiller 1.
QUESTION 69
Part of the Certkiller network is shown below:
Host Certkiller 1 needs to communicate with the email server shown above. What address will be placed in the destination address field of the frame when it leaves Host Certkiller 1?
A. The MAC address of Host Certkiller 1
B. The MAC address of E0 of the router Certkiller C
C. The MAC address of Switch Certkiller B
D. The MAC address of E1 of the router Certkiller C
E. The MAC address of Switch Certkiller A
F. The MAC address of the email server Certkiller D
G. None of the above
Answer: B
Explanation:
Since the email server resides on a different IP subnet than the host Certkiller 1, the host will send the frame to its default gateway. In this case, the router Certkiller C is acting as the default gateway for all hosts on the LAN, so the frame will be sent to its Ethernet interface so that it can be routed to the email server.
QUESTION 70
Part of the Certkiller network is shown below:
In this Certkiller network segment, host Certkiller A needs to send data to Host Certkiller B. Which Layer 2 and Layer 3 destination addresses will be used in this session to send the data from Host Certkiller A to Host Certkiller B?
A. 192.168.60.5 and 0007.0e56.ab2e
B. 192.168.24.2 and 0007.0e84.acef
C. 192.168.24.1 and 0007.0e56.ab2e
D. 192.168.60.5 and 0011.43da.2c98
E. None of the above
Answer: A
Explanation:
When packets leave from the host, the packets contains the source MAC and IP of the host address. The source and destination IP address will not change. Because the host knows that the destination is on another subnet, it will forward the packet to the default gateway device, so the destination MAC address will be of the default gateway, which is the FA0/0 interface of router Certkiller 2.
Which IOS user EXEC command will allow a network technician to determine which router in the path to an unreachable network host should be examined more closely for the cause of the network failure?
A. Certkiller B> telnet
B. Certkiller B > ping
C. Certkiller B > trace
D. Certkiller B > show ip route
E. Certkiller B > show interface
F. Certkiller B > show cdp neighbors
Answer: C
Explanation:
This can perform the trace command. It sends the ping packets to each of the routers on the way to the receiver. The router which doesn't respond will be a potential failure place in this network.
QUESTION 62
A Certkiller office's network topology is shown in the diagram below:
Host Certkiller A needs to communications with the e-mail server shown above. What address will be placed on the destination address field of the frame when it leaves host Certkiller A?
A. The MAC address of Certkiller A
B. The MAC address of switch Certkiller 1
C. The MAC address of the E0 interface of the Certkiller 3 router.
D. The MAC address of the E1 interface of the Certkiller 3 router.
E. The MAC address of switch Certkiller 2
F. The MAC address of the email server
Answer: C
Explanation:
If the destination host is in the remote segment than the router will change the MAC address of the source to its own. The inverse ARP protocol is by default on. Remember that IP address is not changed after forwarding. The MAC address is changed after crossing each broadcast domain.
QUESTION 63
The Certkiller network topology is shown below:
You work as a network engineer at Certkiller .com. The topology of the Certkiller .com network is displayed in the exhibit. Host Certkiller 1 has established a connection with the HTTP server attached to interface E0 of the Certkiller B router. Which of the following statements describe the information contained in protocol data units sent from host Certkiller 1 to this server? (Select three)
A. The destination port number in a segment header will have a value of 80.
B. The destination port number in a segment header will have a unique value greater than or equal to 1023.
C. The destination address of a frame will be the MAC address of the HTTP server interface.
D. The destination address of a frame will be the MAC address of the E0 interface of the Certkiller A router.
E. The destination IP address of a packet will be the IP address of the E0 interface of the Certkiller A router.
F. The destination address of a packet will be the IP address of the HTTP-Server
Answer: A, D, F
Explanation:
HTTP uses TCP port 80, making choice A correct. The source port will be chosen randomly, but not the destination TCP port. The destination IP address will be left unchanged, and since HTTP server is on a remote network, the destination MAC address will be the MAC address of the default gateway ( E0 on Certkiller A).
QUESTION 64
The Certkiller network is shown belod:
In this network, host Certkiller 1 is able to send data to Host Certkiller 2. How will Router Certkiller D handle the data frame received from Host Certkiller 1? (Choose three)
A. Router Certkiller D will strip off the source MAC address and replace it with the MAC address on the forwarding Fast Ethernet interface
B. Router Certkiller D will strip off the source IP address and replace it with the IP address on the forwarding Fast Ethernet interface
C. Router Certkiller D will strip off the destination MAC address and replace it with the MAC address of Host Certkiller 2
D. Router Certkiller D will strip off the destination IP address and replace it with the IP address of Host B
E. Router Certkiller D will forward the data frame out interface Fast Ethernet0/1
F. Router Certkiller D will forward the data frame out interface FastEthernet0/2
Answer: A, C, F
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 65
Two Certkiller hosts are shown below:
Refer to the exhibit above. Host A is communicating with host B. How will the data be addressed when it leaves host A?
A. Source MAC=000A.8A47.E612
Destination MAC=000B.DC04.12F4
Source IP=192.168.23.4
Destination IP=192.168.23.1
B. Source MAC=000A.8A47.E612
Destination MAC=0010.7BE7.FAEF
Source IP=192.168.23.4
Destination IP=192.168.127.7
C. Source MAC=000A.8A47.E612
Destination MAC=000B.DC04.12F4
Source IP=192.168.23.4
Destination IP=192.168.127.7
D. Source MAC=000A.8A47.E612
Destination MAC=0010.7BE7.FAEF
Source IP=192.168.23.4
Destination IP=192.168.23.1
E. None of the above
Answer: B
Explanation:
When packets leave from the host, the packets contains the source MAC and IP of the host address. The source and destination IP address will not change (if it did, the router devices would not know where to send the data). Because the host knows that the destination is on another subnet, it will forward the packet to the default gateway device, so the destination MAC address will be of the default gateway, which is the LAN interface of router Certkiller 1.
QUESTION 66
Exhibit:
Please study the exhibit above carefully. If host Certkiller A sends an IP packet to host Certkiller B, what will the OSI Layer 3 source address be in the packet when it reaches host B?
A. B2:B2:B2:B2:B2:B2
B. A1:A1:A1:A1:A1:A1
C. 10.168.10.99
D. 10.168.11.65
E. C3:C3:C3:C3:C3:C3
F. 10.168.11.88
G. None of the above
Answer: C
Explanation:
When packets transfer from one host to another across a routed segment, the source IP address always remains the same source IP address, and the physical (MAC) address will be the existing router's interface address. Similarly, the destination IP address always remains the same and the destination physical (MAC) address is the destination router's interface address.
QUESTION 67
Exhibit:
Please study the exhibit carefully. If host Certkiller A sends an IP packet to host Certkiller B, what will the source physical (MAC) address be in the frame when it reaches host Certkiller B?
A. A1:A1:A1:A1:A1:A1
B. D4:D4:D4:D4:D4:D4
C. B2:B2:B2:B2:B2:B2
D. 10.168.11.88
E. 10.168.10.99
F. C3:C3:C3:C3:C3:C3
Answer: F
Explanation:
When packets transfer from one host to another across a routed segment, the source IP address always remains the same source IP address, and the source physical (MAC) address will be the existing router's interface address. Similarly, the destination IP address always remains the same and the destination physical (MAC) address is the destination router's interface address.
QUESTION 68
In the network below, host Certkiller A is transferring a file to the FTP server. Point A represents the frame as it goes toward the Certkiller 1 router. What will the Layer 2 destination address be at this point?
A. 192.168.7.17
B. abcd.1123.0045
C. aabb.555.2222
D. 192.168.1.1
E. abcd.2246.0035
Answer: E
Explanation:
For packets destined to a host on another IP network, the destination MAC address will be the LAN interface of the router. Since the FTP server lies on a different network, the host will know to send the frame to it's default gateway, which is Certkiller 1.
QUESTION 69
Part of the Certkiller network is shown below:
Host Certkiller 1 needs to communicate with the email server shown above. What address will be placed in the destination address field of the frame when it leaves Host Certkiller 1?
A. The MAC address of Host Certkiller 1
B. The MAC address of E0 of the router Certkiller C
C. The MAC address of Switch Certkiller B
D. The MAC address of E1 of the router Certkiller C
E. The MAC address of Switch Certkiller A
F. The MAC address of the email server Certkiller D
G. None of the above
Answer: B
Explanation:
Since the email server resides on a different IP subnet than the host Certkiller 1, the host will send the frame to its default gateway. In this case, the router Certkiller C is acting as the default gateway for all hosts on the LAN, so the frame will be sent to its Ethernet interface so that it can be routed to the email server.
QUESTION 70
Part of the Certkiller network is shown below:
In this Certkiller network segment, host Certkiller A needs to send data to Host Certkiller B. Which Layer 2 and Layer 3 destination addresses will be used in this session to send the data from Host Certkiller A to Host Certkiller B?
A. 192.168.60.5 and 0007.0e56.ab2e
B. 192.168.24.2 and 0007.0e84.acef
C. 192.168.24.1 and 0007.0e56.ab2e
D. 192.168.60.5 and 0011.43da.2c98
E. None of the above
Answer: A
Explanation:
When packets leave from the host, the packets contains the source MAC and IP of the host address. The source and destination IP address will not change. Because the host knows that the destination is on another subnet, it will forward the packet to the default gateway device, so the destination MAC address will be of the default gateway, which is the FA0/0 interface of router Certkiller 2.
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