Network Monitoring is the use of a system that constantly monitors a computer network for slow or failing components and that notifies the network administrator (via email, SMS or other alarms) in case of outages or other trouble. Network Monitoring is part of network management.

Network monitoring refers to the practice of overseeing the operation of a computer network using specialized management software tools. It includes a comprehensive user administration in addition to numerous alarm, reporting and data exchange functions. 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 and university IT networks.
Key Features in Network Monitoring
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.