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SingaporeComputer ScienceSyllabus dot point

What is a computer network, and how do LANs and WANs differ?

Define a computer network, distinguish a LAN from a WAN, and state the benefits and drawbacks of networking computers

A focused answer to the O-Level Computing point on networks. What a computer network is, the difference between a LAN and a WAN, common networking hardware, and the benefits and drawbacks of connecting computers.

Generated by Claude Opus 4.86 min answer

Reviewed by: AI editorial process; not yet individually human-reviewed

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  1. What this dot point is asking
  2. The answer
  3. Examples in context
  4. Try this

What this dot point is asking

SEAB wants you to define a computer network, to distinguish a LAN from a WAN, and to weigh the benefits and drawbacks of networking computers. The central idea is that a network connects devices so they can share data and resources, and that networks are classified mainly by the area they cover and who owns them.

The answer

What a network is

A computer network is two or more computers and devices connected together so they can communicate and share resources such as files, printers and an internet connection. The connection can be by cables or wireless (Wi-Fi).

LAN: Local Area Network

A LAN connects devices over a small area, such as a single home, school or office building. It is usually owned and managed by one organisation, using its own cables, switches and wireless access points. LANs are typically fast and cheap to run within that area.

WAN: Wide Area Network

A WAN connects devices over a large area, such as a city, country or the whole world. It often links many LANs together. Because it spans long distances, a WAN usually relies on infrastructure owned by others, such as telephone lines, fibre links or the internet. The internet itself is the largest WAN.

Common networking hardware

  • A switch connects devices within a LAN and directs data to the right one.
  • A router connects different networks together, for example a home LAN to the internet.
  • A network cable or wireless access point carries the data between devices.

Benefits of networking

  • Share resources: one printer or internet connection serves many users.
  • Share files: data is stored centrally and accessed by everyone.
  • Communicate: email and messaging between users.
  • Central management: backups and updates done once for all.

Drawbacks of networking

  • Cost: cables, hardware and setup are expensive.
  • Security risk: malware or an intruder can spread across connected machines.
  • Dependence: if the network fails, many users are affected at once.
  • Management: someone needs the skills to run and secure it.

Examples in context

Example 1. A home network. A house with a router sharing one internet connection among phones, a laptop and a smart TV is running a small LAN. Devices share the connection and can stream to the TV, but if the router fails, everything loses internet at once, showing the dependence drawback.

Example 2. A bank's branches. A bank links the LANs in its many branches into a WAN so any branch can access central account data. This sharing is powerful, but it also means strong security is essential, because a threat reaching the WAN could affect every branch.

Try this

Q1. State what the letters LAN and WAN stand for. [2 marks]

  • Cue. LAN is Local Area Network; WAN is Wide Area Network.

Q2. Give one benefit and one drawback of connecting office computers into a network. [2 marks]

  • Cue. Benefit: sharing resources such as a printer or files; drawback: cost or increased security risk.

Q3. State the difference between a switch and a router. [2 marks]

  • Cue. A switch connects devices within one network; a router connects different networks together (such as a LAN to the internet).

Exam-style practice questions

Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Original4 marks(a) Define a computer network. (b) State two differences between a LAN and a WAN.
Show worked answer →

(a) A computer network is two or more computers (and other devices) connected together so they can communicate and share data and resources such as files, printers and an internet connection.

(b) Two differences:

  • Size and area: a LAN (Local Area Network) covers a small area such as one building or school; a WAN (Wide Area Network) spans a large area, such as a country or the whole world.
  • Ownership and infrastructure: a LAN is usually owned and run by one organisation using its own cables and equipment; a WAN often connects many LANs using third-party infrastructure such as telephone lines or the internet.

Markers reward a clear network definition (connected devices sharing data and resources) and two valid LAN-versus-WAN differences such as area or ownership.

Original5 marksA small office is deciding whether to connect its computers into a network. (a) Give two benefits of networking the computers. (b) Give two drawbacks the office should consider.
Show worked answer →

(a) Benefits include: sharing resources such as a single printer and an internet connection; sharing and accessing files centrally so staff work on the same data; easier communication (email, messaging); and central backup and updates done once for everyone. Any two are acceptable.

(b) Drawbacks include: the cost of cables, hardware and setup; greater security risk, since malware or an intruder can spread across connected machines; dependence on the network, so a failure can stop everyone working; and the need for management by someone with networking skills. Any two are acceptable.

Markers reward two genuine benefits such as resource or file sharing, and two genuine drawbacks such as cost or security risk.

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