Computer Networks

About this unit

This unit explains how computers are connected to share data and resources. It traces the growth of networking from ARPANET to the Internet, classifies networks by the area they cover, and describes the devices and topologies used to build them. It also covers how devices are identified (MAC and IP addresses), how domain names are translated by DNS, and everyday Internet applications such as the web, email, chat and VoIP, together with websites, web servers and web browsers.

Key ideas

• Networks are classified as PAN, LAN, MAN and WAN by the area they cover.
• Devices: modem, Ethernet card, repeater, hub, switch, router and gateway.
• Topologies: bus, star, ring, mesh and tree.
• MAC address (physical, 48-bit) and IP address (logical; IPv4 is 32-bit, IPv6 is 128-bit).
• DNS converts domain names into IP addresses.
• The Internet is the network; the World Wide Web is a service that runs on it.

How to prepare

Make a comparison list of devices (what each does and at which point it is used) and of topologies (advantages and disadvantages). Practise case-study questions that ask which device, topology or network type suits a given campus. Memorise the parts of a URL and the bit sizes of addresses.