1.4 KiB
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Monday, January 13, 2025 |
Ping
ping is perhaps the most basic network debugging tool. It sends
ICMP echo request packets to a recipient host.
If the recipient receives the packet and is configured to reply, it sends an ICMP echo response packet in return.
For example:
$ ping google.com
PING google.com (142.250.200.14) 56(84) bytes of data.
64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=1 ttl=116 time=19.1 ms
64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=2 ttl=116 time=19.2 ms
64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=3 ttl=116 time=19.1 ms
64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=4 ttl=116 time=21.1 ms
The first indicates the IP address of the host you are pinging (once per second, by default). The subsequent lines are the response packets, echoed back from this host.
The icmp_seq is the number of the request in the sequence. If there was to be
a gap in the sequence, this would be the clearest indication of a connection
problem.The packets should not arrive out of order since there is only one
packet being sent per second.
time is the round-trip time - from the sending of the packet to its return to
the sender.
If the packet cannot reach the destination host, the final router to see the
packet retunes a "host unreachable" packet to ping.