Networks and topologies
LANs, WANs, network hardware, the internet and topologies like star and mesh.
Learning Objectives
- 1Describe the characteristics of LANs and WANs
- 2Explain factors that affect network performance
- 3Describe the roles of computers in client-server and peer-to-peer networks
- 4State the purpose of common LAN hardware
- 5Explain how the internet works as a network of networks, including DNS and the Cloud
- 6Compare star and mesh network topologies
LANs and WANs
Think of it like...
A LAN is like your house's own internal plumbing: it's yours, contained, and you control it. A WAN is like the city's water network connecting many houses together, running through shared, third-party infrastructure.
Factors affecting network performance
Client-server and peer-to-peer networks
LAN hardware
- Wireless access point – lets devices connect to the network wirelessly.
- Router – connects different networks together, for example connecting a home network to the internet.
- Switch – connects devices within the same network and sends data directly to the device it's intended for.
- NIC (Network Interface Controller/Card) – hardware inside a device that allows it to connect to a network.
- Transmission media – the physical pathway data travels along, such as cables or radio waves.
| Hardware | Task performed |
|---|---|
| Wireless access point | Allows devices to connect to the network wirelessly. |
| Router | Connects separate networks together (e.g. a LAN to the internet), directing data between them. |
| Switch | Connects devices within a LAN, receiving data and sending it directly to the intended device using its MAC address. |
| NIC | Hardware, built in or added to a device, that allows it to connect to a network. |
| Transmission media | The physical medium data travels through, such as copper/fibre cables or radio waves. |
The internet
Star and Mesh topologies
Exam Phrasing: Use These Exact Phrases
- ✓A LAN covers a small geographical area and typically uses owner-owned hardware
- ✓A WAN covers a large geographical area and connects multiple LANs, often using third-party infrastructure
- ✓Network performance is affected by the number of devices connected and the available bandwidth
- ✓In a client-server network, a server provides services that clients request and use
- ✓In a peer-to-peer network, all devices have equal status with no dedicated server
- ✓DNS converts a URL into the IP address of the server hosting the website
- ✓A switch sends data directly to the device it is intended for, using MAC addresses
- ✓A router connects separate networks together
- ✓In a star topology, all devices connect to a central device; if it fails, the network fails
- ✓In a mesh topology, devices connect directly to multiple others, giving no single point of failure
- 💡If asked for a characteristic of a LAN or WAN, give a defining feature (e.g. "covers a small area", "owner-owned hardware"), not a benefit like "cheaper", examiners specifically distinguish these.
- 💡When identifying a client and server in a scenario, be precise about which computer is requesting a service and which is providing it, and remember a website is not itself a computer.
- 💡Don't confuse a switch with a server: a switch only directs traffic to the correct device, it does not store data or provide services.
- 💡For a star topology diagram: connect every device only to the central device, extra device-to-device connections turn it into a mesh topology by mistake.
- 💡For benefits/drawbacks of wired vs wireless or Cloud vs local, always link your point back to the specific scenario in the question, not just a generic fact.
Wrong:
A switch works the same way as a server
Right:
A switch only forwards data to the correct device using MAC addresses; it does not store data or provide services
Why it matters: OCR examiners flagged this as a common misconception, confusing traffic-directing hardware with a service-providing server.
Wrong:
Drawing extra connections directly between devices in a star topology diagram
Right:
In a star topology, every device connects only to the single central device
Why it matters: Extra device-to-device connections accidentally turn a star topology into a mesh topology.
Wrong:
Stating a benefit (e.g. "cheaper") when asked for a characteristic of a LAN
Right:
A characteristic is a defining feature, e.g. "covers a small area" or "uses owner-owned hardware"
Why it matters: Examiners specifically distinguish between a characteristic and a benefit; answering with the wrong one loses marks.
Wrong:
A website is a server
Right:
A website is hosted on a web server; the server is the computer, the website is what it provides
Why it matters: This mix-up is a common error when identifying the client and server in a scenario.
Question:
A small office has five computers and one printer that all need to connect to the same network. Recommend a network topology and justify your answer. [3]
💡 Attempt this before revealing the answer, practice makes perfect!
Model Answer:
A star topology would be appropriate. All the devices would connect to a single central switch, which makes it simple and low-cost to set up for a small office of this size. It would also be easy to add another computer to the network in future, since a new cable just needs to be connected to the switch.
Mark Scheme:
- 1Identifies star topology
- 2Justifies with ease/low cost of setup for a small number of devices, or ease of adding new devices
- 3Links the justification to the given scenario (a small office)
Tap a card to flip it. Use the arrow keys to move and space to flip.
Exam-style questions. Have a go, then reveal the mark scheme to check your answer.
1.State one characteristic of a LAN.
[1]2.State two factors that can affect the performance of a network.
[2]3.A company has one central computer that stores all files, which staff computers connect to and download from. State whether this is a client-server or peer-to-peer network, and justify your answer.
[2]4.Describe the purpose of DNS.
[2]5.A school wants to connect twenty computers together and wants it to be simple and low-cost to add more computers in the future. Recommend a network topology and justify your answer, referring to one drawback of your choice.
[4]6.A small business is deciding whether to store its files in the Cloud instead of on its own local server. Discuss one advantage and one disadvantage of moving to the Cloud.
[4]7.A small business is setting up a network in a new office. Discuss the factors they should consider when choosing a network topology and whether to use wired or wireless connections.
[8]Extended response · marked in levels, not by counting points
The examiners' reports are the most useful and least read of the three: they say what candidates actually got wrong each year. All files are hosted by OCR.
Past-paper questions grouped by topic
The same OCR questions, sorted by topic rather than by year (via Physics & Maths Tutor).
On a question giving example IP addresses, few candidates gave fully valid addresses. A common IPv4 error was using numbers greater than 255; a common IPv6 error was giving only 6 groups of numbers, or separating groups with full stops instead of colons.
When drawing a star topology diagram, common errors included not labelling every device, connecting a printer to another computer instead of directly to the switch, not clearly identifying the central device, and accidentally adding extra connections that turned the diagram into a mesh topology instead of a star.
On a question about how a switch works, stronger answers explained that the switch uses the MAC addresses of connected devices to send data to the correct destination. A common misconception was that a switch behaves like a server, storing data or providing services to the network.
When asked for a characteristic of a LAN (rather than a benefit), candidates often gave a benefit instead, such as "cheaper" or "can share devices". Stronger answers gave genuine defining characteristics, such as using owner-owned hardware, in comparison with a WAN.
When identifying the client and server in a given scenario, some candidates correctly identified which computer was the client but could not justify it by reference to the correct scenario, and some incorrectly identified a website itself as the server, when a website is not a computer, the web server hosting it is.