In this recipe, we'll adjust the definition of a very important host to ensure that it checks whether the host is up in every three minutes and, if it finds that the host is down as a result of the check failing, it will check again after a minute before it sends a notification about the state to its defined contact. We'll do this by customizing the definition for an existing host.
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.
You should also understand the basics of commands and plugins, in particular the meaning of the
check_command directive. These are covered in the recipes in Chapter 2, Working with Commands and Plugins.