ICMP Message Class and Type

Question 1

Indicates that a datagram could not be delivered to its destination. The Code value provides more information on the nature of the error.

Answer 1

Destination Unreachable

Question 2

Lets a congested IP device tell a device that is sending it datagrams to slow down the rate at which it is sending them

Answer 2

4 Source Quench (Error message)

Question 3

Allows a router to inform a host of a better route to use for sending datagrams

Answer 3

5 Redirect (Error message)

Question 4

Sent when a datagram has been discarded prior to delivery due to expiration of its Time to Live field.

Answer 4

11 Time Exceeded (Error message)

Question 5

Sent in reply to an Echo (Request) message; used for testing connectivity

Answer 5

0 Echo Reply (Error message)

Question 6

Sent by a device to test connectivity to another device on the internetwork. The word Request sometimes appears in the message name.

Answer 6

8 Echo Request (Error message)

Question 7

Used by routers to tell hosts of their existence and capabilities

Answer 7

9 Router Advertisement (Error message)

Question 8

Used by hosts to prompt any listening routers to send a Router Advertisement

Answer 8

10 Router Solicitation (Informational)

Question 9

Sent by a device to request that another send it a timestamp value for propagation time calculation and clock synchronization. The word Request sometimes appears in the message name

Answer 9

13 Timestamp (Request) (Informational)

Question 10

Sent in response to a Timestamp (Request) to provide time calculation and clock synchronization information.

Answer 10

14 Timestamp Reply (Informational)

Question 11

Originally used to request configuration information from another device. Now obsolete.

Answer 11

15 Information Request (Informational)

Question 12

Originally used to provide configuration information in response to an information Request message. Now obsolete

Answer 12

16 Information Reply (Informational)

Question 13

Used to request that a device send a subnet mask.

Answer 13

17 Address Mask Request (Informational)

Question 14

Contains a subnet mask sent in reply

Answer 14

18 Address Mask Reply (Informational)

Question 15

Used to implement the experimental enhanced traceroute utility

Answer 15

30 Traceroute (Informational)

Question 16

Indicates that a datagram could not be delivered to its destination. Code value provides more information on the nature of the error.

Answer 16

3 Destination Unreachable (Error Message)