What is a Computer Network ? Networking 101

In this post, we go over the fundamentals of computer networking as we prepare for the CCNA exam.

A computer network is composed of many different systems connected together. It can be further described as a vast system of interconnected devices (what we call the Internet), think inter-connected-networks. This network or rather the internet, communicate to each other through what we call IP addresses and Protocols (TCP/IP) which we will go over later. These devices communicate to exchange resources, information, and general data (e.g. files, data, printing) and other general TCP/IP related services. Essentially, a Network connects millions of devices together through the Inter-connected-network or rather the Internet.

Basic Computer Network

To begin, let’s work with a simple example. We see two computers connected physically. These two computers can talk to each other.

In this simple and basic network example, the two computers are directly connected using a cable. Even though it’s only two computers we still call this a network. It is a network with two devices. In the real world, a network is much more sophisticated but the principle remains the same.

Growing Your Network

Now we take that very simple concept and grow it. Where we had two connect devices, we now have four connected devices. Now in order to grow from 2 connected computers to 4 connected computers, we now need a device to connect these devices together.

Now all four of the devices on this simple network is able to communicate with one another through the specific network device.

These network devices that allow computers to talk to each other can be called routers, switches, or hubs.

There are names for many different networks but to start off your knowledge of Networking, we’ll focus on the most important, LAN & WAN.

The other networks consist of:

LAN (Local Area Network)
PAN (Personal Area Network)
MAN (Metropolitan Area Network)
WAN (Wide Area Network)

Local Area Network

We can also call this a LAN. A Local Area Network (LAN) is a network that contains a small area of network devices. It is generally small in scope and limited to a geographic area such as a test lab, class, office, school, or building.

Wide Area Network

LAN is a the smallest definition of a network, as it relates to the local area. As the network grows and involves more clusters of networks (LANs) we begin to see a bigger and broader network. This is what we call the WAN or Wide Area Network (WAN). A WAN connect networks in larger geographic areas which entails more networks and more devices, such as New York, the United States of America, or the world, think World Wide Web (the Internet!).

Instead of a single cable connecting two computers or multiple cables connecting four computers, we now have a situation where we are connection hundreds, thousands, millions of devices through large cables (transport cables, fiber cables) these large cables are connected over the ocean or in sewers.