Monitoring refers to the practice of overseeing the operation of a computer network using specialized management software tools. Network monitoring systems are used to ensure availability and overall performance of computers (hosts) and network services. These systems are typically employed on larger scale corporate IT infrastructures.
A network monitoring system is capable of detecting and reporting failures of devices or connections. It normally measures the processor (CPU) utilization of hosts, the network bandwidth utilization of links, and other aspects of operation. It will often send messages (sometimes called watchdog messages) over the network to each host to verify it is responsive to requests. When failures, unacceptably slow response, or other unexpected behavior is detected, these systems send additional messages called alerts to designated locations (such as a management server, an email address, or a phone number) to notify system administrators.