The purpose of computer networks, the difference between LANs and WANs, client-server and peer-to-peer models, and common network topologies.

A Unit 1 networks question. A LAN (local area network) connects computers over a small geographical area, such as a single building or site, usually using the organisation's own cables and equipment (1 mark). A WAN (wide area network) connects computers over a large geographical area, such as across cities or countries, often using infrastructure provided by third parties, with the internet being the largest example (1 mark). A benefit of a network is that users can share resources such as files, printers and an internet connection, or communicate easily (1 mark), and another valid benefit is central management of security and backups (1 mark). Markers reward small versus large area and a clear benefit. A common error is to define a WAN as simply a bigger LAN without mentioning the geographical scale or third-party links.

A Unit 1 network-model question. In a client-server network, one or more powerful computers act as servers that provide services, files and resources, while the other computers are clients that request them (1 mark); this allows central management, security and backups, but the server is a single point of failure and costs more (1 mark). In a peer-to-peer network, all computers are equal (peers) and share resources directly with each other, with no dedicated server (1 mark); this is cheaper and simpler for small networks, but it is harder to manage, secure and back up as it grows (1 mark). Markers reward the server-and-clients structure versus equal peers, plus a sensible consequence of each. A common error is to say peer-to-peer has no computers sharing, when in fact every peer shares directly.