When neither the -4 nor -6 options are specified on the command-line, one
would expect the check_ping plugin to try both (as most programs do).
Instead, if it finds an AAAA record for the hostname given, it will *only*
try IPv6, and fail if no IPv6 connectivity is available.
e.g. on a fully dual-stacked host:
chrisb@cob:~$ /usr/lib/nagios/plugins/check_ping -H www.google.co.uk -w 3000.0,80% -c 5000.0,100% -p 1
PING OK - Packet loss = 0%, RTA = 19.56 ms|rta=19.555000ms;3000.000000;5000.000000;0.000000 pl=0%;80;100;0
but on a machine with IPv4 only:
chrisb@squeeze-vm:~$ /usr/lib/nagios/plugins/check_ping -H www.google.co.uk -w 3000.0,80% -c 5000.0,100% -p 1
CRITICAL - Network Unreachable (www.google.co.uk)
We noticed this earlier today, when Google started publishing an AAAA record
for www.google.co.uk et al. Happy IPv6 day ;)
I realise this testcase may stop working after today, but any host that
publishes both A and AAAA records should do (e.g. ftp.uk.debian.org)
Set to 'minor' severity, since using the -4 and -6 options works, and if
you're specifically testing for v4/v6 connectivity you'd be using them.