NETACAD 13 ICMP Flashcards

1
Q

Describe ICMP messages and their function

A

The TCP/IP suite provides for error messages and informational messages when communicating with another IP device. These messages are sent using ICMP. The purpose of these messages is to provide feedback about issues related to the processing of IP packets under certain conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What ICMP messages are common to both ICMPv4 and ICMPv6

A

Host reachability, Destination or Service Unreachable, and Time exceeded.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe an ICMP host messages

A

An ICMP Echo Message tests the reachability of a host on an IP network. The local host sends an ICMP Echo Request to a host. If the host is available, the destination host responds with an Echo Reply. This is the basis of the ping utility.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the ICMP Destination Unreachable message

A

When a host or gateway receives a packet that it cannot deliver, it can use an ICMP Destination Unreachable message to notify the source. The message will include a code that indicates why the packet could not be delivered.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the ICMPv4 Time Exceeded message

A

An ICMPv4 Time Exceeded message is used by a router to indicate that a packet cannot be forwarded because the Time to Live (TTL) field of the packet was decremented to zero. If a router receives a packet and decrements the TTL field to zero, it discards the packet and sends a Time Exceeded message to the source host. ICMPv6 also sends a Time Exceeded in this situation. ICMPv6 uses the IPv6 hop limit field to determine if the packet has expired. Time Exceeded messages are used by the traceroute tool.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe messages between a) an IPv6 router and an IPv6 device and b) IPv6 devices

A

The messages between an IPv6 router and an IPv6 device including dynamic address allocation include RS and RA. The messages between IPv6 devices include the redirect (similar to IPv4), NS and NA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe ping and the different information it provides on a connection

A

Ping (used by IPv4 and IPv6) uses ICMP echo request and echo reply messages to test connectivity between hosts. To test connectivity to another host on a network, an echo request is sent to the host address using the ping command. If the host at the specified address receives the echo request, it responds with an echo reply. As each echo reply is received, ping provides feedback on the time between when the request was sent and when the reply was received. After all the requests are sent, the ping utility provides a summary that includes the success rate and average round-trip time to the destination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How can ping be used to test internal configuration of IPv4 or IPv6 on the local host.

A

Ping the local loopback address of 127.0.0.1 for IPv4 (::1 for IPv6).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How can the pin test be used to test the ability of a host to communicate on the local network

A

by pinging the IP address of the default gateway of the host. A successful ping to the default gateway indicates that the host and the router interface serving as the default gateway are both operational on the local network.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can Ping be used to test the ability of a local host to communicate across an internetwork.

A

The local host can ping an operational IPv4 host of a remote network.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Briefly describe traceroute testing

A

Traceroute (tracert) generates a list of hops that were successfully reached along the path. This list provides verification and troubleshooting information. If the data reaches the destination, then the trace lists the interface of every router in the path between the hosts. If the data fails at some hop along the way, the address of the last router that responded to the trace can provide an indication of where the problem or security restrictions are found. Traceroute makes use of a function of the TTL field in IPv4 and the Hop Limit field in IPv6 in the Layer 3 headers, along with the ICMP time exceeded message.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is round trip time

A

The round-trip time is the time a packet takes to reach the remote host and for the response from the host to return.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly