In this chapter, we looked at various ways of running service checks on remote servers and the use cases where these ways can be useful. In general, passive checks are less commonly used compared to active checks. But the checks that are expected to run for a relatively longer time before they return the status should be setup as passive checks. As a rule of thumb, publicly available services should be monitored with active checks, while the rest can be over SSH/NRPE or passive checks depending on the nature of the service checks. As a fallback method, whenever it is required to run checks remotely, checking by SSH is the most flexible and preferred way of executing checks remotely.

We will take a look at the most common system resource and performance checks for Linux and Windows hosts, and network devices, so as to ensure proper health of our servers.