NOS (Network Operating System)
The primary software associated with LAN is NOS. it is usually resides on the File Server (discussed latter in the chapter) and provides service services to add new devices to a network, install applications, diagnose network problems, assemble network usage statistics, and route messages. It may also include programs to manage each of the dedicated servers in a network, provide e-mail services and allow remote user to access LAN resources through dial-up lines.