Types of computer networks

• Wide Area Network or WAN

  • Covers countries and continents

• Local Area Network or LAN

  • Covers a small area such as a school, home or office

• A server is a special computer designed to carry out one specific job for another computer. There are several types of server including:

  • File servers

  • Print servers

  • Mail servers

  • Application servers

  • Web servers

• A file server is is used as a central file storage. Users are given specific rights (such as read and write) to certain parts of the file server.
• A print server is used to share a printer on the network
• A mail server is used to send and receive emails
• An application server is one that allows applications to be stored once on a server and then loaded on to the client computer's RAM when it is needed
• Web servers are connected to the Internet and are used to host web and deliver webpages and files that can be accessed from any computer using a web browser.

• At the centre of a client-server network is a server that is responsible for allocation of resources

• The client(s) access resources that the server manages and provides users with access to these resources

• In a peer-to-peer network each computer has it's own resources and security settings. Each computer is either directly (through a cable from each computer to the next and back) or indirectly (through many network hubs or switches) connected to each other.

Client-server advantages:

• One central file storage means that it is easier to set access rights to files and to back up the files

• The same files can be accessed from any computer

Client-server disadvantages:

• Cost – initial set up is expensive

• Requires someone to manage the server

Peer-to-peer advantages:

• Easy setup: most computers are ready to go out of the box

• Cheap to setup: you need a few computers and cables and you’re good to go

Peer-to-peer disadvantages:

• Backups are difficult because files are stored on different computers across the network

• Security of files is not easy to enforce since it is not in a single central location

• There are several types of networking devices, each with its own specific purpose within a network topology. The following devices are used to make up a network:
  • Hub
  • Switch
  • Router

• A hub is a very basic device that allows multiple users to share one connection. 
• Any data sent to a hub is distributed to all devices on the hub. It's then up to each device to figure out if it was meant for them. 
• Hubs are very simple to build but also very slow compared with the more advanced switch.

• A switch is a more advanced version of a hub whereby the ports are given the full bandwidth of the network connection they are connected to.
• They achieve this by using a technique known as polling where they move through each port on the switch very quickly and gives the full bandwidth of the port for a short period then moves on.
• Each device only receives the data it requested with a switch.

• Routers are used to connect multiple networks together. For example, your home router will connect your home network (often built-in to the router too) to the Internet.
• Routers are very common now, but back in the early 2000s most people had one connection to the Internet through a modem.

• There are four common ways networks are organised.