Ping results are sometimes wrong

Brett Glass brett at lariat.org
Sat May 17 08:58:55 PDT 2003


Just noticed that FreeBSD's ping program was giving me inaccurate stats when
pinging hosts on the local subnet (but not on remote subnets). Some
investigation has revealed why: the delay for the very first ping includes the
time (if any) it takes to use ARP to discover the MAC address of the target.
This introduces an outlying data point that messes up the stats; it makes them
look as if there are extra delays or congestion on the network.

Perhaps the program should make sure that the MAC address of the target (if
it's on the local network) has been resolved before starting to ping?

--Brett Glass


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