Network monitoring is spying for a good cause. Actually, it's something you want at least one of your systems to be doing. While your other systems are performing their vital functions, you need to set aside at least one computer or set of computers to monitor network activity. Think of this as policing your network traffic.
This network monitoring must be done by a system that is always on. Your system should have dedicated power lines or, at the very least, backup generators attached to it. This is the most critical part of your network, since it is the one that sounds the alarm if something is wrong.
Monitoring takes note of slow or failing systems and notifies the network administrator of such occurrences. Such notifications can take the form of email messages, pager alerts, or plain old phone calls. No matter what form they take, network problem messages should take the highest priority.
Network monitoring can alert a network administrator to problems caused by overloaded systems, crashed servers, lost network connections, virus or malware infections, and power outages, among other things. This last instance is why the system needs to have backup power: You can’t very well be notified of a power outage if the system that is supposed to do the notifying also loses its power.
In order to monitor a network, a “ping” or test is commonly sent to each computer or system on the network. If the system does not respond or takes too long to respond, the system does its job by notifying the network administrator of the problem. Pings are intended to be replied to instantaneously; anything else hints at a larger problem than just the absence of a ping.
Other network monitoring software makes a practice of regularly taking virtual snapshots of the network’s workflow. Any irregularities in this workflow are logged and, if they are serious enough, reported to the network administrator. Some well-known software manufacturers make monitoring applications that are standalone products; other manufacturers embed the software in larger applications or software suites.
Network monitoring can also be as basic as tracking the flow of visitors to and from a website, also tracking such statistics as time of visit, number of pages on the site visited, and entry and exit URLs. This kind of monitoring isn’t necessarily the kind that reports problems, unless the network administrator programs it to; rather, website software tracks and reports web activity for analysis.