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ICT 04174.1

Networks, network hardware and the internet

LAN versus WAN, the devices that connect them, and intranet versus internet.

Review these first

Learning objectives

What you need to be able to do

Teacher-mapped phrasing — check against the official Cambridge syllabus for exact wording.

  • 4.1.1Describe LANs, WLANs and WANs and the hardware needed to build a network.
  • 4.1.2Distinguish between the internet, an intranet and an extranet.

6 minute read

Networks, network hardware and the internet

Types of network

  • LAN (local area network) — covers a small geographical area such as one building or site, typically owned by one organisation.
  • WLAN — a wireless LAN, using radio rather than cables.
  • WAN (wide area network) — covers a large geographical area, often connecting LANs in different cities or countries. The internet is the largest WAN.

Network hardware

  • NIC (network interface card) — lets a device connect to a network; each has a unique MAC address.
  • Switch — connects devices within a LAN and sends data only to the intended recipient, using MAC addresses.
  • Router — connects different networks together and directs data between them using IP addresses. It is the device that joins a home LAN to the internet.
  • Hub — an older device that broadcasts data to every connected device, which wastes bandwidth and is less secure than a switch.
  • Modem — converts digital signals to analogue and back for transmission over telephone lines.
  • WAP (wireless access point) — allows wireless devices to join a wired network.

Internet, intranet and extranet

  • Internet — the global public network of interconnected networks, open to everyone.
  • Intranet — a private network within one organisation, using the same web technologies but accessible only to its members. Used for internal notices, documents and systems.
  • Extranet — an intranet extended to allow controlled access by selected outsiders, such as suppliers or customers.

Wired versus wireless

Wired is generally faster, more reliable and more secure, as an intruder needs physical access. Wireless offers mobility and avoids cabling costs, but signals can be intercepted and are weakened by distance and walls.

Think of it like this

A switch is a postal sorter that reads each envelope and delivers only to the right door; a hub is someone reading every letter aloud in the corridor. Both get the message through — one of them tells everybody.

Worked examples

Method, step by step

A school wants staff to access internal documents and policies, but not allow the public to see them. Which type of network should it use, and why?

  1. 1The requirement is access limited to members of one organisation.
  2. 2An intranet is a private network using web technologies, accessible only within the organisation.
  3. 3The internet would make the documents publicly available, which is not wanted.

An intranet — it uses familiar web technology but is private to the school, so only staff can reach the documents while the public cannot.

Common misconceptions

  • Using "internet" and "World Wide Web" as synonyms. The internet is the global network infrastructure; the web is one service running on it, alongside email and file transfer.
  • Confusing switch and router. A switch connects devices *within* one network; a router connects *between* networks.
  • Thinking an intranet is simply "a small internet". It is private and restricted to one organisation, which is the defining feature.

In the exam

  • For "give two differences between a LAN and a WAN", contrast geographical area covered and ownership, and optionally transmission speed and cost.
  • Security questions about wireless expect a specific mitigation — encryption, a strong password, WPA, or MAC address filtering — not just "make it secure".