LAN – know that these usually cover relatively small geographical areas.

The idea

A local area network (LAN) connects devices within a relatively small geographical area, such as a single home, a school, an office or one building. The key idea is scale: the network is local, so cabling or short-range wireless can link the devices, and the owner usually controls the hardware. Contrast this with a wide area network (WAN), which spans large distances such as between towns or countries. In a multiple-choice question, look for the phrase describing the size of the area covered and match it to 'relatively small'. A school computer suite sharing a printer and file server is a typical LAN; a bank linking branches across a country is not. Learn to justify the choice by pointing to the small area and the shared local resources, and reject options that describe national or global coverage.

What earns the marks

• Defines a LAN as a network covering a relatively small geographical area.
• Gives a valid example such as a home, school, office or single building.
• Contrasts LAN scale with WAN, which covers large geographical areas.
• Uses the small-area clue in a scenario to justify selecting LAN.

Common mistakes and how to put them right

• Treating any wireless network as a WAN.

  Put it right: Scale decides the type, and a small-area wireless network is still a LAN.

• Describing a LAN as covering a country or the world.

  Put it right: That scale describes a WAN.

• Ignoring the word 'relatively'.

  Put it right: LAN size varies, but it is small compared with a WAN.

Exam tips

• Highlight the geographical clue in the question before choosing an option.
• Check your choice against a concrete example such as one school building.
• Eliminate options describing links between distant sites, which indicate a WAN.