Networks Exam Practice

This lesson brings together all the topics from OCR J277 Section 1.3 (Computer Networks) and provides exam-style questions with model answers. Use this to consolidate your knowledge and practise the skills needed for Paper 1.

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Key Topics to Revise

Topic	Key Points
LAN vs WAN	LAN: small area, single owner; WAN: large area, third-party infrastructure
Client-server vs P2P	Client-server: central server; P2P: all devices are equal
Topologies	Star (central switch), mesh (multiple paths), bus (shared backbone)
Network hardware	NIC (MAC address), switch (LAN, MAC), router (between networks, IP), WAP (wireless)
Internet, DNS, hosting	DNS resolves domain names to IPs; hosting stores websites on servers
Protocols	TCP/IP, HTTP/S, FTP, SMTP, IMAP
TCP/IP layers	Application, Transport, Internet, Network Interface
Packet switching	Data split into packets, different routes, reassembled at destination
Wired vs wireless	Ethernet/fibre (fast, reliable) vs WiFi/Bluetooth (mobile, convenient)

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Practice Question 1: LAN and WAN (3 marks)

Question: Explain the difference between a LAN and a WAN.

Model Answer:

A LAN (Local Area Network) covers a small geographical area such as a single building or school campus, and is owned and managed by one organisation. [1 mark]

A WAN (Wide Area Network) covers a large geographical area such as multiple cities or countries, and typically uses infrastructure owned by third-party telecommunications companies. [1 mark]

The internet is the largest example of a WAN, connecting millions of LANs worldwide. [1 mark]

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Practice Question 2: Network Topologies (4 marks)

Question: Compare star and bus network topologies, explaining one advantage and one disadvantage of each.

Model Answer:

Star topology:

• Advantage: If one device or cable fails, only that device is affected; the rest of the network continues working. [1 mark]
• Disadvantage: If the central switch fails, the entire network goes down — it is a single point of failure. [1 mark]

Bus topology:

• Advantage: Requires less cabling than a star topology, making it cheaper to set up. [1 mark]
• Disadvantage: If the backbone cable fails, the entire network fails, and as more devices are added, collisions increase, slowing the network. [1 mark]

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Practice Question 3: Network Hardware (4 marks)

Question: Describe the purpose of each of the following network devices: (a) Switch (b) Router

Model Answer:

(a) Switch: A switch connects devices within a LAN and directs data to the specific device it is intended for. It does this by reading the MAC address in the data frame and forwarding it only to the port connected to that device. This is more efficient than a hub, which broadcasts data to all devices. [2 marks]

(b) Router: A router connects different networks together (e.g. a LAN to the internet/WAN). It reads the IP address in each data packet and determines the best route to forward the packet to the destination network. Routers also perform NAT (Network Address Translation) to translate between private and public IP addresses. [2 marks]

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Practice Question 4: Protocols (3 marks)

Question: State the protocol used for each of the following tasks: (a) Sending an email (b) Retrieving an email from a mail server (c) Securely browsing a website

Model Answer: