Learning Nagios 4

One of the most important challenges in system monitoring is to detect and report any malfunctioning system or device as soon as possible, so that you as an administrator are aware of the problem before a user runs into one.
Nagios is a powerful monitoring tool that enables organizations to identify and resolve IT infrastructure problems before they affect critical business processes. It monitors your entire IT infrastructure to ensure systems, applications, services, and business processes are functioning properly. In the event of a failure, Nagios can alert the technical staff of the problem, allowing them to begin remediation processes before outages affect business processes, end-users, or customers.