Knowledge Organiser: LAN and WAN

LAN: Local Area Network — covers a small geographic area (single building/campus)
WAN: Wide Area Network — covers large geographic areas (cities, countries, global)
Network: Two or more devices connected to share resources and communicate
Router: Device that connects a LAN to the Internet (WAN)
Switch: Device that connects devices within a LAN

LAN: small area (one building), privately owned, fast (1–10 Gbps), low cost
WAN: large area (cities/countries), third-party telecoms infrastructure, slower, expensive monthly fees
The Internet is the largest example of a WAN
LAN infrastructure (cables, switches, WiFi) owned by the organisation
WAN infrastructure owned by telecoms companies (BT, Virgin, etc.)
LAN is more secure — physical access needed to connect
ALWAYS give BOTH size AND ownership when comparing LAN and WAN

Why LAN is faster: Short cable distances mean less signal degradation and delay
Why WAN costs more: Organisation must pay telecoms companies monthly rental fees for infrastructure
LAN + WAN together: Most organisations have a private LAN that connects to the Internet via a WAN link (router)
Exam answer structure: State size difference AND ownership difference for full marks

Only giving one difference between LAN and WAN: Exam questions award marks for both geographic size AND ownership — a LAN covers a small area AND is privately owned; a WAN covers a large area AND uses third-party infrastructure
Saying the Internet is a WAN: The Internet is the largest example of a WAN, but not all WANs are the Internet — a company linking two offices in different cities uses a private WAN
Confusing routers and switches: A switch connects devices within a LAN; a router connects different networks together (e.g. LAN to the Internet)
Saying LANs cannot be wireless: A LAN can use either wired (Ethernet) or wireless (Wi-Fi) connections — the defining feature is geographic size, not the medium used

LAN and WAN, Knowledge Organiser