CCNA2 - Module 8 Exam Answers （05/09/2008 14:30）

1 、 How does a source host use ICMP to confirm that a destination host is reachable?

• The source host sends an ICMP echo request to the destination router which responds with an ICMP echo reply confirming the reachability of the destination host.

• The source host sends a data packet and receives an ICMP host unreachable packet from the destination host if the data packet cannot be delivered.

• The source host sends an ICMP packet with a TTL value of 1 and receives an ICMP reply with a TTL value of 0 from the destination host.

• The source host sends an ICMP echo request and receives an ICMP echo reply from the destination host.

2 Which type of message is generated by a host when the ping command is entered? • ICMP echo request

• ICMP echo reply

• UDP echo request

• UDP error message

3

Which of the following start the test of destination reachability? • echo request issued by source

• echo reply issued by source

• echo request issued by destination

• echo reply issued by destination

4 Which two statements are true regarding ICMP? (Choose two.)

• ICMP provides reliability for the TCP/IP protocol stack.

• ICMP is a component of the TCP/IP protocol stack.

• ICMP notifies the sender that data transmission errors have occurred.

• ICMP is connection-oriented.

• ICMP messages are propagated to all intermediate devices.

5 How does ICMP improve data transfer reliability in IP networks?

• Each router in the path reads ICMP packets and uses the information to update routing tables.

• ICMP can correct many network problems as they occur.

• ICMP error messages are returned to the sending device when a packet is dropped by a router.

• ICMP packets report the intermediary devices that a packet passed through before failure occurred.

6 Which layer protocols provide reliability for IP when needed?

• ICMP and ping

• RIP and TTL

• upper layer protocols

• lower layer protocols

• Internet layer protocols

• network access layer protocols

7 Which devices along a data transmission path are notified by ICMP when delivery failures occur?

• source devices only

• destination devices only

• intermediary devices

• source and destination devices

• source, intermediary, and destination devices

8 When a datagram is processed by a router on the path from source to destination, what happens to the value in the TTL field?"

• It is increased by one.

• It is decreased by one.

• It stays the same.

• It is reset to 0.

• Nothing.

9 Which condition could cause a fragmentation needed ICMP destination unreachable message to be sent?

• A low bandwidth WAN link has become congested with IP traffic.

• A packet is forwarded from a Token Ring network to an Ethernet network.

• A network is not reachable because of faulty routing information.

• The address specified by the sending host is nonexistent.

10、

Workstation 1 sent a data packet to Workstation 4. It never arrived because Fa0/0 interface went down on Router C. How will the devices handle this failure?

• Workstation 4 will send an error message to Router C and Workstation 1 that it did not receive the packet.

• Router C will use ICMP to send a message back to Workstation 1 indicating that the packet could not be delivered.

• Router C discards the packet without providing notification to any device.

• Router C uses ICMP to correct the failure and transmits the data to Workstation 4.

• Workstation 1 will use ICMP to correct the problem and then notify Router C to continue the transmission.

11 Which three conditions must be met in order for host to host communication over an internetwork to occur on IP networks? (Choose three.)

• The routing protocols configured on the source and destination networks must be the same.

• A default gateway must be properly configured on the hosts and local networks.

• Intermediary devices, such as routers, must be present on the network and have knowledge of how to reach the destination network.

• The source and destination host subnet masks must match.

• The IP addresses of the hosts must be in the same network or subnet as their respective gateway devices