In this recipe, we'll learn how to arrange Nagios Core configuration to send notifications about problems with a host or service only after a check has been repeated a certain number of times and failed each time.
This can be an ideal arrangement for non-critical hosts that occasionally have "blips" or short outages and only become problematic if they remain down after repeated checks. It prevents sending notifications on the first check, only sending them if the problem turns out to be consistent.
You should have a Nagios Core 4.0 or newer server, with at least one host configured already. We'll use the example of
sparta.example.net, a host defined in its own file. We'll arrange for it to send us notifications only after a total of five failed host checks.