Network Operating System (NOS)

A network operating system (NOS) is an operating system that manages network resources: essentially, an operating system that includes special functions for connecting computers and devices into a local area network (LAN). The NOS manages multiple requests (inputs) concurrently and provides the security necessary in a multiuser environment. It may be a completely self-contained operating system, such as NetWare, Unix, Windows 2000, or Mac OS X, or it may require an existing operating system in order to function (e.g., Windows 3.11 for Workgroups requires DOS; LAN Server requires OS/2; LANtastic requires DOS). In addition to file and print services, a NOS may also offer directory services and a messaging system (email), as well as network management and multiprotocol routing capabilities.

History Network Operating System
Early microcomputer operating systems such as CP/M, MS-DOS and classic Mac OS were designed for one user on one computer. Packet switching networks were developed to share hardware resources, such as a mainframe computer, a printer or a large and expensive hard disk. As local area network technology became available, two general approaches to handle sharing of resources on networks arose.

Historically a network operating system was an operating system for a computer which implemented network capabilities. Operating systems with a network stack allowed personal computers to participate in a client-server architecture in which a server enables multiple clients to share resources, such as printers. Early examples of client-server operating systems that were shipped with fully integrated network capabilities are Novell NetWare using the Internetwork Packet Exchange (IPX) network protocol and Banyan VINES which used a variant of the Xerox Network Systems (XNS) protocols.

These limited client/server networks were gradually replaced by Peer-to-peer networks, which used networking capabilities to share resources and files located on a variety of computers of all sizes. A peer-to-peer network sets all connected computers equal; they all share the same abilities to use resources available on the network. The most popular peer-to-peer networks as of 2020 are Ethernet, Wi-Fi and the Internet protocol suite. Software that allowed users to interact with these networks, despite a lack of networking support in the underlying manufacturer's operating system, was sometimes called a network operating system. Examples of such add-on software include Phil Karn's KA9Q NOS (adding Internet support to CP/M and MS-DOS), PC/TCP Packet Drivers (adding Ethernet and Internet support to MS-DOS), and LANtastic (for MS-DOS, Microsoft Windows and OS/2), and Windows for Workgroups (adding NetBIOS to Windows). Examples of early operating systems with peer-to-peer networking capabilities built-in include MacOS (using AppleTalk and LocalTalk), and the Berkeley Software Distribution.

Today, distributed computing and groupware applications have become the norm. Computer operating systems include a networking stack as a matter of course. During the 1980s the need to integrate dissimilar computers with network capabilities grew and the number of networked devices grew rapidly. Partly because it allowed for multi-vendor interoperability, and could route packets globally rather than being restricted to a single building, the Internet protocol suite became almost universally adopted in network architectures. Thereafter, computer operating systems and the firmware of network devices tended to support Internet protocols.

Types of Network Operating Systems
Unlike operating systems, such as Windows, that are designed for single users to control one computer, network operating systems (NOS) coordinate the activities of multiple computers across a network. The network operating system acts as a director to keep the network running smoothly.

The two major types of network operating systems are:

Peer-to-Peer Client/Server Nearly all modern networks are a combination of both. The networking design can be considered independent of the servers and workstations that will share it.

Peer-to-Peer Peer-to-peer network operating systems allow users to share resources and files located on their computers and to access shared resources found on other computers. However, they do not have a file server or a centralized management source (See fig. 1). In a peer-to-peer network, all computers are considered equal; they all have the same abilities to use the resources available on the network. Peer-to-peer networks are designed primarily for small to medium local area networks. Nearly all modern desktop operating systems, such as Macintosh OSX, Linux, and Windows, can function as peer-to-peer network operating systems.

Features and Tasks of Network Operating Systems
The salient features of network operating systems are:

• Basic operating system features support like protocol support, processor support, hardware detection and multiprocessing support for applications
• Security features like authentication, restrictions, authorizations and access control
• Features for file, Web service, printing and replication
• Directory and name services management
• User management features along with provisions for remote access and system management
• Internetworking features like routing and WAN ports
• Clustering capabilities

Common tasks associated with network operating systems include:

• User administration
• System maintenance activities like backup
• Tasks associated with file management
• Security monitoring on all resources in the network
• Setting priority to print jobs in the network

Advantages and Disadvantages of Network operating systems

Advantages of Network operating systems

• Highly stable due to central server.
• Provide good security.
• Upgradation of new technology and hardware can be easily implemented in the network.
• Provide remote access to servers from different locations.

Disadvantages of Network operating systems

• Depend on the central location to perform the operations.
• High cost to buying server.
• Regular updating and maintenance are required.