Linux.com: Ping: ICMP vs. ARP Dec 27, 2005, 01 :00 UTC (8 Talkback[s]) (6134 reads) (Other stories by Gerard Beekmans)
"Network and system administrators are well-versed in using the ping utility for troubleshooting purposes, but where do you turn when ping doesn't do the trick?
"Pinging a host is usually the first step in determining if the host is properly connected to the network. If the host does not respond to a ping request, the host is usually assumed to be offline.