Re: [tlug] Ping vs www server

["Stephen J. Turnbull" <stephen@example.com>]

Scott Robbins writes:

 > This means that it's online but that the web server is down.  Ping just
 > tests physical connectivity, that is, if a machine is connected to a
 > network.

Actually, what ping tests is whether the domain implements the
Internet ICMP echo protocol.  This *usually* is equivalent to physical
connectivity, but not always.  Try pinging turnbull.sk.tsukuba.ac.jp,
then browsing http://turnbull.sk.tsukuba.ac.jp/.

 > The 80 refers to port 80.  That's the standard port for a web
 > server to use to listen for connections.  

BTW, there are ping (fping, maybe?) and traceroute (tcptraceroute)
tools that can be used to check whether a given host is responding via
TCP as well as the lower-level ICMP.