ICND2 Chapter 09

Question 1

ICMP message: Destination Unreachable

Answer 1

Tells the source host that there is a problem delivering a packet.

Question 2

ICMP message: Time Exceeded

Answer 2

The time that it takes a packet to be delivered has expired; so the packet has been discarded.

Question 3

ICMP message: Redirect

Answer 3

The router sending this message has received a packet for which another router has a better route. The message tells the sender to use the better route.

Question 4

ICMP message: Echo Request; Echo Reply

Answer 4

Used by the ping command to verify connectivity.

Question 5

ICMP Unreachable Code: Network Unreachable

Answer 5

Router; There is no match in a routing table for the packet’s destination.

Question 6

ICMP Unreachable Code: Host unreachable

Answer 6

Router; the packet can be routed to a router connected to the destination subnet; but the host is not responding.

Question 7

ICMP Unreachable Code: Can’t fragment

Answer 7

Router; the packet has the Don’t Fragment bit set; and a router must fragment to forward the packet.

Question 8

ICMP Unreachable Code: Protocol unreachable

Answer 8

Host; the packet is delivered to the destination host; but the transport layer protocol is not available on that host.

Question 9

ICMP Unreachable Code: Port unreachable

Answer 9

Host; the packet is delivered to the destination host; but the destination port has not been opened by an application.

Question 10

ping Command Code: !

Answer 10

ICMP Echo Reply received

Question 11

ping Command Code: .

Answer 11

Nothing was received before the ping command timed out

Question 12

ping Command Code: U

Answer 12

ICMP unreachable (destination) received

Question 13

ping Command Code: N

Answer 13

ICMP unreachable (network/subnet) received

Question 14

ping Command Code: M

Answer 14

ICMP Can’t Fragment message received

Question 15

ping Command Code: ?

Answer 15

Unknown packet received