Network Operating Systems (NOS) and Essential LAN Components

Network Operating Systems (NOS) Fundamentals

The NOS, or Network Operating System, is the software that enables a computer system to communicate with other computers within a network. Frequently, the NOS is built-in; however, some advanced systems require additional installation.

Evolution of the NOS Architecture

1. Initial Stage

   Before the need for networked PCs, communications were possible through serial ports, utilizing specialized software known as *communications programs*.

2. Integration of Communications Programs

   In advanced versions of DOS, communications programs were integrated into the OS itself, eliminating the need to acquire separate broadcast products.

3. Added Networking Software

   Networking products required installation on top of another OS to interact with other nodes using a network adapter (typical for Novell networks).

4. Networking Software Integrated with the OS

   This stage is characterized by the complete integration of all networking software within the OS. There is no need to install special software; the OS includes everything necessary. This is the current standard for systems like Windows, Apple, and Unix, which are now perfectly integrated.

Understanding Network Domains

The domain is an extension of the working group concept. A domain may consist of a working group, but the concept of a domain is accompanied by other features such as **centralized network management**, ease of equipment administration, and control of usernames and passwords. A Windows domain further annexes capabilities for resource management, user control, and desktop management.

Directory Services and LDAP Protocol

A directory service is a hierarchical database of organized objects containing information that is easily accessible and useful to the OS, the network, or users requesting system resources. The directory service is accessed through special interrogation protocols to query the data. The most widely used base protocol is **LDAP** (Lightweight Directory Access Protocol). LAN networks years ago began to benefit from this technology, allowing all information about the network and its resources to reside within a centralized directory service.

Network Adapters: The Physical Interface

Network adapters are the fundamental element in the composition of the LAN. Each physical network adapter is a hardware interface between the platform or computer system and the physical transmission environment. The adapter may or may not be incorporated with the basic hardware platform of the computer's operating system. A computer can have one or more network cards to allow different configurations or to connect to different networks simultaneously.