Network Operating System or popularly known as NOS runs on a server and and provides server the capability to manage data, users, groups, security, applications, and other networking functions. The primary purpose of the network operating system is to allow shared file and printer access among multiple computers in a network.
Examples: Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD.
How it is different from stand alone OS
Standalone OS usage the capability of the local system only where as NOS can use the capability of the server which may be more powerful then the local system.
Advantages of network operating systems
Centralized servers are highly stable.
Security is server managed.
Upgrades to new technologies and hardwares can be easily integrated into the system.
Remote access to servers is possible from different locations and types of systems.
Disadvantages of network operating systems
High cost of buying and running a server as compare to standalone.
Dependency on a central location for most operations and single point of failure.
Regular maintenance and updates are required.