Nagios Support Forum

Nagios was running fine until a remote server went down. The server came back up but Nagios could not ping it and NSClient+= checks could not
find it. The sysadmin rebooted the Nagios server and everything came back. This happened several times in one week. When this happens
the other server cannot be pinged from the command line. The Nagios server is on the latest version of Ubuntu server. Nothing unusual looking in the network configs.
This is my 12th Nagios install, never seen this before. Was it just dumb luck?

Thanks.

I've seen something similar before, if/when it happens next then open up the /usr/local/nagios/var/nagios.log file and look for orphaned check results. If this is the case then a second instance of Nagios has started without the previous instance stopping.

In most instances where I've seen this it's the result of a script stopping or restarting nagios without checking to see if it has stopped properly before starting a new process. I've also seen this happen on a virtualised Nagios server that had an uptime of nearly a year sitting on an ESX host with memory performance and stability issues... migrating it off that host and restarting the server resolved the problem in that instance.