In this recipe, we'll learn how to arrange a Nagios Core configuration such that after a certain number of repetitions, notifications for problems on hosts or services are escalated to another contact, instead of (or in addition to) the normally defined contact. This is done by defining a separate object type called a host or service escalation.
This kind of setup could be useful for alerting more senior networking staff of an unsolved problem that a less experienced person is struggling to fix and can also function as a "safety valve" to ensure that problem notifications for hosts eventually do reach someone else if they remain unfixed.
You should have a Nagios Core 4.0 or newer server, with at least one host or service configured already, and at least two contact groups — one for the first few notifications, and one for the escalations. You should understand how notifications are generated and sent to the