What are the type Code values for an ICMP echo request?
What are the type Code values for an ICMP echo request?
Internet Control Message Protocol (ICMP) Parameters
- Type 0 — Echo Reply.
- Type 1 — Unassigned.
- Type 2 — Unassigned.
- Type 3 — Destination Unreachable.
- Type 4 — Source Quench (Deprecated)
- Type 5 — Redirect.
- Type 6 — Alternate Host Address (Deprecated)
- Type 7 — Unassigned.
What is ICMP echo request?
The Echo Request simply means that the host to which it is addressed should reply to the packet. The Echo Reply is the ICMP message type that should be used in the reply. The Request includes some data, which can be specified by the ping command; whatever data is sent in the Echo Request is sent back in the Echo Reply.
What are the type Code values for an ICMP echo request and Echo Reply packet?
Echo and Echo-Reply An echo packet has type 8 set in the ICMP header, and the reply uses type zero. Neither have any codes defined, so the code field in the header is always set to zero. The second four bytes of the header includes two 16-bit fields; The Identifier and the Sequence.
What does a Type 3 code 0 of ICMP message reveals?
ICMP error messages of Type: 3 represent a “destination unreachable” situation, where code values clarify the type of unreachability, as follows: 0 = net unreachable; 1 = host unreachable; 2 = protocol unreachable; 3 = port unreachable; 4 = fragmentation needed and DF is set; 5 = source route failed.
What are ICMP error codes?
ICMP Error messages
| ICMP message type | Description | Codes |
|---|---|---|
| 1 | Destination Unreachable | 0 – 8 |
| 2 | Packet Too Big | 0 |
| 3 | Time Exceeded | 0 – 1 |
| 4 | Parameter Problem | 0 – 10 |
What command sends ICMP echo request packets?
The ping command
The ping command operates by sending Internet Control Message Protocol (ICMP) Echo Request messages to the destination computer and waiting for a response. The two major pieces of information that the ping command provides are how many of those responses are returned and how long it takes for them to return.
What is ICMP echo request and reply?
Echo-Request and Reply: ICMP packets of echo request and reply are used to test the network layer of destination. In other words, the host at the destination is switched on or off. We can also check the network layer of all the devices on the way from sender to destination.
What are the ICMP type and code numbers?
Many of the types of ICMP message are now obsolete and are no longer seen in the Internet. Some important ones which are widely used include: Echo Reply (0), Echo Request (8), Redirect (5), Destination Unreachable (3), Traceroute (30), Time Exceeded (11). Many of these ICMP types have a “code” field.
