From LQWiki

Ping is a network troubleshooting tool that sends ICMP echo requests that is used for testing connectivity between nodes. It, of course, is named after sonar pings that a submarine uses to detect other ships. It is sometimes said to stand for Packet INternet Groper, but this is a backronym.

One difference between the MS-DOS/Windows version of this tool and the Linux version is that, by default, the DOS version quits after 4 pings, the Linux version keeps pinging indefinitely. (Stop it with Ctrl C, or run it with the -c 4 option to stop after 4 pings.)

Examples

ping www.google.com

• Pings Google.
• Note that ping can accept IP addresses or domain names.

TroubleShooting

Problem: The DNS entry has changed (maybe it is a dynamic one from no-ip.com), but ping still tries to reach the old ip-address.

Reason: The IP address is cached.

Solution: Restart the name service cache daemon:

/etc/init.d/nscd restart

See also

• traceroute