OxfordAQA IGCSE Computer Science: Computer Networks — Practice Questions (9210)

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs — examination boards hold copyright in their own papers. Use these alongside the official past papers available free from your board.

Related: Computer networks study guide | Computer networks revision notes

These questions cover section 3.5 of the OxfordAQA International GCSE Computer Science (9210) specification, which is assessed on Paper 2.

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Section A: networks

1. Define the term computer network. [1]

2. A small business is deciding whether to network its eight computers. Discuss two benefits and two risks. [4]

3. (a) Give two differences between a LAN and a WAN. [2] (b) State the biggest example of a WAN. [1]

4. A college is connecting two buildings 800 metres apart, and computers within each building. State, with a reason, the type of cable you would use for (a) the link between the buildings (b) the connections inside a classroom. [4]

5. A café wants to offer customers a wireless network. Discuss one benefit and two risks of a wireless network compared with a wired one. [3]

6. Explain what the term WLAN means and how it relates to Wi-Fi. [2]

Section B: topologies

7. (a) Draw (or describe) a star topology with four computers and a printer. [2] (b) Explain one advantage of a star topology over a bus topology. [2] (c) Explain one disadvantage of a bus topology. [2]

Section C: protocols

8. Define the term protocol. [1]

9. State the most suitable protocol for each task: (a) uploading files to a web server (b) sending an email from a phone to a mail server (c) reading the same email inbox on a phone and a laptop (d) paying for goods on a shopping website. [4]

10. Explain why a video call application might use UDP rather than TCP. [3]

11. Explain what is meant by saying that Ethernet is a “family of protocols”. [1]

Section D: security and the TCP/IP model

12. For each security method, explain what it is and give an example of when it would be used: (a) authentication (b) encryption (c) firewall (d) MAC address filtering. [8]

13. Explain how two of these methods can work together to protect a school network. [2]

14. (a) Name the four layers of the TCP/IP model in order, starting with the layer nearest the user. [1] (b) Describe the main function of the transport layer and the network layer. [2] (c) State the layer at which each operates: (i) IMAP (ii) IP (iii) UDP. [3] (d) State which layer contains the network interface card (NIC). [1]

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Answers

1. Two or more computers or devices connected together so that they can communicate and share resources [1].

2. Benefits (any two): files can be shared and stored centrally; a printer and Internet connection can be shared; staff can communicate by email or messaging; central backups [2]. Risks (any two): malware can spread from one computer to the others; hackers may gain unauthorised access to data; if the server or switch fails, everyone is affected; setting up and managing the network costs money [2].

3. (a) Any two: a LAN covers a relatively small geographical area, a WAN a wide area [1]; a LAN is usually owned and managed by a single person or organisation, a WAN is often under collective or distributed ownership [1]. (b) The Internet [1].

4. (a) Fibre-optic cable [1]: it carries data over long distances with high bandwidth and is not affected by electrical interference [1]. (b) Copper cable [1]: it is cheaper and easier to install, and the short distances within a room do not need the performance of fibre [1].

5. Benefit: customers can connect any device without cables and move around the café [1]. Risks (any two): signals can be intercepted by anyone within range, so data could be read if not encrypted [1]; unauthorised users might connect; slower or less reliable connection due to distance, walls or interference [1].

6. WLAN stands for wireless local area network – the generic term for this type of network [1]. Wi-Fi is a trademark for a family of related wireless networking protocols used to create a WLAN [1].

7. (a) Each of the four computers and the printer is connected by its own cable to a central switch [2] (1 for the central switch, 1 for separate cables to each device). (b) If one cable fails only that device is affected [1], whereas a break in a bus backbone stops the whole network [1]. (Or: the switch sends data only to the destination device, so performance is better and there are fewer collisions.) (c) All devices share one cable, so data collisions increase and performance falls as traffic grows [1]; a fault in the main cable stops every device communicating [1].

8. A set of rules that govern how data is transmitted and received by devices [1].

9. (a) FTP [1] (b) SMTP [1] (c) IMAP [1] (d) HTTPS [1].

10. UDP does not set up a connection or check that every packet arrives [1], so it has less delay than TCP [1]. In a video call, a few lost packets cause only a brief glitch, while waiting for lost packets to be resent would make the call lag [1].

11. Ethernet is not one single protocol but a group of related protocols for wired networks [1].

12. 2 marks each (1 for the explanation, 1 for a suitable example): (a) Checking a user’s identity before access is given, e.g. a username and password when logging on to a school computer, or a code sent to a phone. (b) Scrambling data using a key so that if it is intercepted it cannot be understood, e.g. encrypting Wi-Fi traffic with WPA2, or HTTPS for online banking. (c) Hardware or software that monitors incoming and outgoing traffic and blocks it according to rules, e.g. blocking connections from unknown external addresses. (d) Allowing or blocking devices based on the physical (MAC) address in their network adapter, e.g. only allowing school-owned laptops to join the network.

13. E.g. MAC address filtering ensures only school devices can connect [1], and authentication then ensures only registered students and staff can log on, so an attacker would need both an approved device and valid login details [1].

14. (a) Application, transport, network, link [1]. (b) Transport: sets up the communication between the two hosts, which agree settings such as the size of packets [1]. Network: addresses and packages the data for transmission and routes the packets across the network [1]. (c) (i) Application [1] (ii) Network [1] (iii) Transport [1]. (d) Link layer [1].

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Where marks are usually lost

• Answering “which protocol” questions with HTTP when the task needs security (HTTPS).
• Saying IMAP sends email: SMTP sends, IMAP retrieves.
• Giving security methods without an example of when each is used, when the question asks for both.
• Stating benefits of wireless without any risk when asked to “discuss”.

Frequently asked questions

Does 9210 include POP3? No. The email protocols named in the 9210 specification are SMTP and IMAP.

Do I need to know the alternative names for the TCP/IP layers? No. The specification uses application, transport, network and link, and says students will not be expected to know the alternative names.