LANs, WANs and the Internet

In its most basic form, a network is two or more computer systems which are linked together by some form of transmission medium that enables them to share information. It does not matter whether the network contains two or thousands of machines; the concept is essentially the same. A network will provide services to its users. These services may include access to shared files and folders, network printing and database applications.

To attempt to clarify the size and nature of individual networks, the industry has developed terms that broadly define the scope of the network.




Network Components

Despite the variations in size and design all networks have certain components in common. The key elements include the transmission medium, the clients and the servers (or hosts) that hold the shared data.

Transmission Media

Information must be transferred using some form of media. Typically, this takes the form of a cable but 'wireless' media using technologies such as infrared, microwave and radio can provide the same function.

Client

Network clients are the computers on the network that allow users to request the shared resources on the servers. Clients are often referred to as workstations.

Server

A server provides the shared resources on the network and allows clients to access this information. There are a number of different types of server:

• File and Print Servers share their resources amongst client computers
• Application Servers provide centralized processing - for example, database platforms such as SQL Server and Oracle
• Messaging Servers provide email functionality
• Network Servers provide network services, such as name resolution services, or authentication services
• Terminal Servers - a special server which provides access to the network for terminal based systems

In many situations, one machine might provide some, or even all, of these functions. In larger networks, machines may be dedicated to a subset of these functions. However, they are all servers.

Host

Host is a TCP/IP networking term meaning any device communicating on the network (similar to node).

Node

A node is any device, such as a workstation, server or printer that can communicate on the network.