ICMP is short for Internet Control Message Protocol. It is one of mail internet protocols. This network layer protocol provided control, troubleshooting and error messaging. It works over IP, but it is not transport layer, like TCP and UDP.
Ping, tracert and pathping are some of tools on this level. Ping – identifies existing and available systems.
When system send PING command to some IP address, if everything is OK, address should send respond. In case that destination does not exist, transfer routes are not correct or ping port is closed / hidden on destination, there will be no answer. PING can be also used to check DNS translation.
PING can be used on next two ways:
- PING IPaddress
- PING servername
The ping command operates by sending Internet Control Message Protocol (ICMP) Echo Request to some destination.
Syntax: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS]
[-r count] [-s count] [[-j host-list] | [-k host-list]]
[-w timeout] [-R] [-S srcaddr] [-c compartment] [-p]
[-4] [-6] soucename
-? help will be displayed.
-t Pinging destination host until ctrl+C is pressed.
-a if possible, it will show hostname of some address.
-n number of sent ping request.
Usual use is for example: ping www.google.com or ping 220.127.116.11
Answer should be something as Ping www.google.com
Pinging www.google.com [18.104.22.168] with 1500 bytes of data: Reply from 22.214.171.124: bytes=1500 time=68ms TTL=52 Reply from 126.96.36.199: bytes=1500 time=68ms TTL=52 Reply from 188.8.131.52: bytes=1500 time=65ms TTL=52 Reply from 184.108.40.206: bytes=1500 time=66ms TTL=52 Reply from 220.127.116.11: bytes=1500 time=70ms TTL=52 Ping statistics for 18.104.22.168: Packets: Sent = 5, Received = 5, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 65ms, Maximum = 70ms, Average = 67ms
Ping wird ausgeführt für google.com [2a00:1450:4001:81b::200e] mit 32 Bytes Daten: Antwort von 2a00:1450:4001:81b::200e: Zeit=23ms Antwort von 2a00:1450:4001:81b::200e: Zeit=19ms Antwort von 2a00:1450:4001:81b::200e: Zeit=19ms Antwort von 2a00:1450:4001:81b::200e: Zeit=20ms Ping-Statistik für 2a00:1450:4001:81b::200e: Pakete: Gesendet = 4, Empfangen = 4, Verloren = 0 (0% Verlust), Ca. Zeitangaben in Millisek.: Minimum = 19ms, Maximum = 23ms, Mittelwert = 20ms
You can see is destination reachable, how stable is communication and you can check does DNS works, is DNS correctly configured on source, is used destination name correct/exiting and what is IP address for some address name.
Traceroute identifies network paths. It shows path where some packet is traveling, usually routers. it can be used to identify network problems.
Pathping is one more tools of ICMP, it is combination of tracert and ping commends.