Networks: 4.1.2 understand different types of networks (LAN, WAN)

The idea

Networks are classified by the area they cover and who controls them. A local area network, or LAN, covers a small area such as one building or campus, for example a school where computers, printers and a file server are linked by the school's own cabling and wireless access points. A wide area network, or WAN, covers a large geographical area and typically links separate LANs using infrastructure that the organisation does not own, such as leased telecoms lines. A bank with branches in several cities runs a WAN so each branch LAN can reach the central accounts system. The key distinctions are scale, ownership of the communication medium and the hardware needed: a LAN usually uses owned cabling, switches and wireless access points, while a WAN depends on external links and routers.

What earns the marks

• A LAN covers a small area such as a single building or site, while a WAN covers a large geographical area such as a country or the world.
• A LAN is usually owned and managed by the organisation, whereas a WAN typically uses external communication links that the organisation does not own.
• A WAN commonly connects two or more separate LANs together, for example linking branch offices to a head office.
• LAN hardware includes owned cabling, switches and wireless access points, while WAN links rely on routers and telecommunications infrastructure.
• Correctly classifying a described scenario, such as a single school site as a LAN and a bank's nationwide branch links as a WAN.

Common mistakes and how to put them right

• Treating LAN and WAN as different in purpose rather than in size and ownership.

  Put it right: , both share data and resources, but a LAN is small and locally owned while a WAN spans a large area using external links.

• Assuming a WAN must be wireless.

  Put it right: , WAN links often use cables, satellites or leased lines, and wireless is simply one possible transmission method.

• Thinking the internet is the only possible WAN.

  Put it right: , any large-area network linking sites, such as a company's private links between offices, is a WAN.

• Believing a LAN cannot connect to the internet.

  Put it right: , a LAN commonly connects to the internet through a router, which is a link to a much larger WAN.

Exam tips

• Look for the size of the area and who owns the connections; these two clues usually decide whether the scenario is a LAN or a WAN.
• When a question describes several sites linked together, check whether each site is a LAN joined by a WAN rather than labelling the whole system a LAN.
• Avoid answers that describe wireless or wired transmission as the definition of LAN or WAN, because both types can use either method.