Identifying LANs and WANs

To decide whether a network in a scenario is a LAN or a WAN, look at two things: the area covered and who owns or manages the hardware and infrastructure. The number of computers is not a classifying feature: having many devices does not make a network a WAN, and a WAN may connect only two sites.

Justifying your choice

Give separate points. First state the area: a LAN covers a small geographical area, often one building or site, while a WAN covers a large geographical area. Then state ownership: a LAN usually uses hardware owned or managed by the organisation, while a WAN often uses infrastructure not owned by the organisation, such as communication links rented from a provider. Keeping the two points separate makes your justification clearer than one long, mixed sentence.

Defining a WAN

Repeating the name in a definition adds no detail. A WAN is a network that covers a large geographical area and/or uses infrastructure not owned by the organisation. Infrastructure not owned by the organisation includes links supplied by another company.

Why a network is a LAN

• It covers a small geographical area or a single building.
• It uses no external infrastructure, or only infrastructure within the organisation.
• The hardware is owned or managed by the organisation.
• The hardware is dedicated to that organisation and not shared with other organisations.
• It connects individual nodes, such as computers and printers, rather than connecting networks.

For example, a hospital site runs its own network: the laptops carried on the wards, the scanner in the imaging department and the printer in the pharmacy are joined by cabling and switches the hospital owns. That is a LAN — one site, hardware the hospital owns, and no links from another company needed to join those devices. If the hospital then sends a patient's scan to a specialist unit 200 miles away, over a fibre link it rents from a communications company, that link is a WAN: it crosses a large distance and the hospital does not own the infrastructure the scan travels over.