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This lesson introduces the two main types of computer networks — LAN (Local Area Network) and WAN (Wide Area Network) — as required by OCR J277 Section 1.3.1. Understanding the differences between these network types is essential for your GCSE exam.
A computer network is two or more devices connected together so they can communicate and share resources (such as files, printers, and internet connections).
Networks can be as small as two computers connected in a home, or as large as millions of devices connected across the world (the internet).
A LAN is a network that covers a small geographical area, such as a single building, a school, or an office.
| Feature | Detail |
|---|---|
| Geographical area | Small — a single room, building, or campus |
| Ownership | Owned and managed by one organisation or individual |
| Hardware | Switches, routers, access points, cables |
| Speed | High — typically 100 Mbps to 10 Gbps |
| Cost | Lower setup cost (shorter cables, fewer devices) |
| Examples | School network, home network, office network |
A typical school LAN might include:
LANs use physical cables (typically Ethernet cables — Cat5e or Cat6) and/or wireless connections (WiFi) to connect devices. The key networking device in a LAN is the switch, which directs data to the correct device.
A WAN is a network that covers a large geographical area, connecting LANs that may be in different cities, countries, or continents.
| Feature | Detail |
|---|---|
| Geographical area | Large — across cities, countries, or the entire world |
| Ownership | Typically relies on infrastructure owned by third-party telecommunications companies |
| Hardware | Routers, modems, leased lines, fibre optic cables, satellites |
| Speed | Variable — depends on the connection type and distance |
| Cost | Higher — requires leased lines or subscription to ISP services |
| Examples | The internet (the largest WAN), a company network spanning multiple offices |
The internet is the largest and most well-known WAN. It connects billions of devices worldwide using a combination of:
A WAN is typically not owned by a single organisation. Instead, it uses infrastructure provided by Internet Service Providers (ISPs) and telecommunications companies.
| Feature | LAN | WAN |
|---|---|---|
| Area | Small (single building/site) | Large (cities/countries/global) |
| Ownership | Owned by one organisation | Uses third-party infrastructure |
| Speed | High (100 Mbps - 10 Gbps) | Variable (often slower) |
| Cost | Lower setup cost | Higher (leased lines, ISP fees) |
| Security | Easier to secure (controlled environment) | Harder to secure (data travels over public networks) |
| Example | School network | The internet |
flowchart LR
subgraph LAN1[School LAN - one site, one owner]
PC1[PC] --- SW1[Switch]
PC2[PC] --- SW1
SRV1[(File Server)] --- SW1
SW1 --- RT1[Router]
end
subgraph LAN2[Office LAN - one site, one owner]
PC3[PC] --- SW2[Switch]
PC4[PC] --- SW2
SW2 --- RT2[Router]
end
RT1 ---|ISP link| WAN((WAN / Internet<br/>third-party infrastructure))
RT2 ---|ISP link| WAN
OCR Exam Tip: You may be asked to explain whether a given network is a LAN or a WAN. The key distinguishing factors are: geographical size and ownership. A LAN covers a small area and is owned by one organisation. A WAN covers a large area and typically uses third-party infrastructure.
There are many reasons for connecting computers into a network:
| Advantage | Explanation |
|---|---|
| Resource sharing | Devices can share printers, scanners, and internet connections |
| File sharing | Users can access shared files from any connected device |
| Communication | Email, instant messaging, and video conferencing |
| Centralised management | Software updates and security can be managed centrally |
| Centralised backup | Files stored on a server can be backed up centrally |
| Disadvantage | Explanation |
|---|---|
| Security risks | Networks can be targeted by hackers and malware |
| Cost | Network hardware, cabling, and maintenance cost money |
| Single point of failure | If the server goes down, all users may be affected |
| Complexity | Networks require specialist knowledge to set up and manage |
| Dependence | If the network fails, users may be unable to work |
Key Vocabulary: LAN, WAN, network, switch, router, ISP, Ethernet, WiFi, server.
Scenario: "BrightShoes Ltd" is a UK shoe retailer with 12 branches across England, a head office in Birmingham, and a warehouse in Leicester. Each branch has 4 till PCs, 1 back-office PC, a Wi-Fi printer and a router connecting to the ISP. The head office has 40 staff PCs, 3 servers (file, email, payroll), and a secure link to the warehouse stock system. Explain where LANs end and WANs begin, and describe the total architecture. Approximately 350 words.
Model walk-through:
Each branch is a LAN. The 4 till PCs, the back-office PC, the printer, and the router sit in one building, are owned by BrightShoes, and are connected by Cat6 Ethernet cabling plus one internal WAP. Geographical footprint: a single shop unit. The LAN can deliver ~1 Gbps between till and back-office PC because it uses the branch's own switch. Twelve shops means twelve separate LANs.
The head office is also a LAN. 40 staff PCs + 3 servers in a single office building = a gigabit LAN with redundant switches. Staff log in to an authentication server; files are served from the file server.
The warehouse is a LAN. Smaller than head office, but still its own LAN (stock scanners, a couple of PCs).
Linking everything together is a WAN. BrightShoes does not own the fibre between Birmingham and each shop; instead, the company buys:
The combined corporate network spans ~200 miles and relies on telecommunications infrastructure owned by BT, Virgin Media, and other ISPs. That makes it a WAN.
Key comparison:
| Feature | Branch LAN | BrightShoes WAN |
|---|---|---|
| Geographical area | One shop unit | UK-wide, 12+ sites |
| Ownership | BrightShoes | BrightShoes for endpoints only; ISPs for the links |
| Speed | ~1 Gbps within the shop | Variable (10-1000 Mbps per site) |
| Cost | One-off cabling + switch | Ongoing ISP and leased-line fees |
| Security scope | Easy — inside the shop | Harder — traffic crosses the public internet, so VPN encryption is essential |
The public internet is itself the largest WAN, and the site-to-site VPN rides on top of it to stitch BrightShoes' LANs into one logical corporate network.
Misconception: "The internet and a WAN are the same thing, and any network that uses Wi-Fi is automatically a WAN because it is wireless."
Reality: The internet is the largest and most famous WAN, but not the only one. A bank, a hospital trust, or a retailer can build its own private WAN using leased lines and VPNs — it is still a WAN even though it is not the public internet. Equally, Wi-Fi has nothing to do with LAN versus WAN. A home Wi-Fi network covering one house is a LAN. The terms LAN and WAN describe geographical scope and ownership, not the connection medium. You can have a wired LAN, a wireless LAN, a wired WAN (fibre), or a wireless WAN (satellite).
Exam question (6 marks): Explain the difference between a LAN and a WAN, using a concrete example of each. Your answer should refer to geographical area, ownership, and at least one advantage and one disadvantage of each type.
"A LAN is a local area network and a WAN is a wide area network. A LAN is small and a WAN is big. A school has a LAN and the internet is a WAN. A LAN is fast and a WAN is slow. A WAN covers lots of countries."
Examiner commentary: The basic definitions and one example of each are given, but the discussion of ownership is missing entirely, and advantages/disadvantages are not properly paired with each type. "Fast" and "slow" are assertions without detail. Marks awarded: around 2 out of 6.
"A LAN (Local Area Network) covers a small geographical area such as a single school or office building, and is owned by one organisation. For example, a school network connecting the ICT room, library, and staff room is a LAN.
A WAN (Wide Area Network) covers a large geographical area across cities, countries, or the world, and typically uses third-party telecommunications infrastructure (fibre, satellites). The internet is the largest WAN.
Advantage of a LAN: High speed and low latency because the network is short and owned by one organisation. Disadvantage of a LAN: Limited reach — useful only within the building. Advantage of a WAN: Connects users across huge distances, enabling email, web browsing, and cloud services. Disadvantage of a WAN: Slower and more expensive because it depends on ISPs and leased lines."
Examiner commentary: A well-organised answer addressing all the required aspects (area, ownership, advantage, disadvantage) with a concrete example of each. Vocabulary is correct. Could mention security differences. Marks awarded: around 4-5 out of 6.
"A LAN is a network covering a small, contained geographical area (one building or campus) and owned and managed by a single organisation. Example: a secondary school LAN connecting around 300 devices via gigabit switches to a shared file server, all owned by the school.
A WAN spans a large geographical area such as multiple cities or countries and relies on infrastructure owned by telecoms providers, usually accessed via leased lines, broadband, or site-to-site VPNs. The internet is the world's largest WAN, but a single company's private WAN linking its offices via VPN is also a WAN.
LAN advantages: high bandwidth (1-10 Gbps), low latency, lower cost per device, easier to secure because all hardware is under one organisation's control. LAN disadvantage: geographically limited; remote workers need extra technology (VPN) to connect.
WAN advantages: global reach, enabling email, cloud services, and inter-office collaboration; highly resilient because of redundant routes. WAN disadvantages: variable speed (shared public infrastructure); ongoing subscription costs; data travels over third-party networks, so encryption (e.g. HTTPS, VPN) is essential to maintain security."
Examiner commentary: Excellent answer with precise technical detail, concrete examples, and balanced advantages/disadvantages for both types. Security implications and encryption are correctly introduced. Marks awarded: 6 out of 6.
When tackling LAN vs WAN questions, keep a mental checklist of four discriminators: area, ownership, speed and security. Examiners reward candidates who link each discriminator to a concrete scenario rather than simply reciting definitions. A school LAN, a home Wi-Fi, and a corporate VPN all make good reference points. Remember that ownership — not size — is often the deciding factor: a university campus covering two square kilometres is still a LAN because the university owns the cabling, while a private network linking two offices across one city is a WAN because it crosses ISP infrastructure.
This content is aligned with OCR GCSE Computer Science (J277) specification section 1.3 Computer networks, connections and protocols. For the most accurate and up-to-date information, please refer to the official OCR specification document.