Early this morning I got alerts from several of our nagios installations saying they couldnt reach www.google.com. I logged into a production machine from my phone and cheked it was still talking to the internet properly. They went back to sleep with an inkling this maybe an issue with World IPv6 Launch day.
When I woke up refreshed and ready for action I went an investigated and it would seem that on our servers check_ping will default to resolving the AAAA record which isnt good when you dont have IPv6 connectivity. So the easy fix is to specify -4 to check ping. Although I'm tempted to just remove the check since if the internet is that broken the alert cant be sent anyway.