WAN – know that these usually cover a wide geographic area.

The idea

A wide area network (WAN) connects devices or networks across a wide geographic area, such as between cities, countries or continents. Because the distance is large, a WAN usually relies on external telecommunications infrastructure, for example leased lines, rather than cabling owned entirely by one organisation. Contrast this with a LAN, which covers a small area such as a single building or campus. A useful method is to judge the geographic span: if the network links sites far apart, it is a WAN. The Internet is the largest WAN, linking networks worldwide. In a multiple-choice question, choose the option describing a network spanning a wide geographic area, and reject options describing a small local network, a single computer or a device-to-device link over a few metres.

What earns the marks

• States that a WAN usually covers a wide geographic area.
• Gives examples of scale such as linking cities, countries or continents.
• Recognises that WANs typically use external telecommunications infrastructure over long distances.
• Contrasts the wide span of a WAN with the small span of a LAN.

Common mistakes and how to put them right

• Describing a WAN as covering a small area such as one room.

  Put it right by stating a WAN spans a wide geographic area.

• Confusing a WAN with a LAN when the network is confined to one building.

  Put it right by noting a LAN covers a small area.

• Assuming a WAN needs no external infrastructure.

  Put it right by noting long-distance links usually rely on telecommunications providers.

Exam tips

• Use the phrase 'wide geographic area' to confirm the correct option.
• Eliminate options describing networks limited to one building or a few metres.
• Check whether the option mentions linking distant sites, which signals a WAN.