Cambridge IGCSE · 0478

Computer Science

Networks and the internet — Paper 1

Name: ____________________Date: October 4, 2026

1.
In a star network topology, how are devices connected? A Each device connects to a central switch or hub B Devices connect in a single loop C All devices share one single cable D Every device connects directly to every other device
[1 mark] · no calculator
Marking points
- Selects A: every device connects individually to a central switch or hub.
Examiner tip: In a star topology, if one device's cable fails, only that device loses connection; the rest of the network is unaffected.
2.
Which protocol is primarily responsible for ensuring data packets are transmitted reliably and reassembled in the correct order across a network? A HTTP B TCP C HTML D DNS
[1 mark] · no calculator
Marking points
- Selects B: TCP breaks data into packets, checks for errors, and reassembles them in the correct order.
Examiner tip: TCP handles reliable delivery and ordering; IP handles addressing and routing of each packet.
3.
Explain the purpose of DNS (Domain Name System) when a user types a website address into a browser.
[2 marks] · no calculator
Marking points
- Explains that DNS translates a human-readable domain name into its corresponding IP address.
- Explains that the browser needs this IP address to locate and connect to the correct web server.
Examiner tip: DNS works like a phone book, converting a memorable name into the numeric address computers actually use.
4.
A website displays a padlock icon and uses 'https://' in its address. What does this indicate? A The site is free of malware B Data sent between the browser and server is encrypted C The site loads faster than others D The site does not use cookies
[1 mark] · no calculator
Marking points
- Selects B: HTTPS encrypts data exchanged between the browser and the server.
Examiner tip: HTTPS protects data in transit; it does not by itself guarantee the site's content is safe or malware-free.
5.
Explain the difference between a computer virus and a worm, in terms of how each spreads.
[2 marks] · no calculator
Marking points
- Explains that a virus attaches itself to a host file or program and needs that file to be run or shared to spread.
- Explains that a worm is standalone and can self-replicate and spread across a network without needing a host file or user action.
Examiner tip: A virus needs a carrier and a user action; a worm actively spreads itself across connected systems.
6.
Explain what a phishing attack is, and state one way a user can protect themselves against it.
[2 marks] · no calculator
Marking points
- Explains that phishing involves a fraudulent message pretending to be from a trustworthy source, aiming to trick the victim into revealing personal or financial information or clicking a malicious link.
- States a valid protection, such as checking the sender's address carefully, not clicking suspicious links, or verifying directly with the organisation before responding.
Examiner tip: Phishing relies on impersonation and urgency; the strongest defence is verifying the sender independently before acting.
7.
Explain why a company should encrypt sensitive customer data before transmitting it over the internet.
[2 marks] · no calculator
Marking points
- Explains that encryption scrambles the data into an unreadable form using a key or algorithm.
- Explains that this protects confidentiality: even if the data is intercepted in transit, it cannot be understood without the decryption key.
Examiner tip: Encryption protects data in case it is intercepted; it is a different control from authentication, which checks who is allowed to access it.
8.
A student copies text from a website directly into their coursework without acknowledging the source. Analyse two ethical issues raised by this action.
[4 marks] · no calculator
Marking points
- Identifies plagiarism: presenting someone else's work or ideas as one's own.
- Explains that this is academically dishonest, since the coursework no longer reflects the student's own understanding.
- Identifies copyright infringement: using someone's intellectual property without permission or credit.
- Explains that this may be unlawful depending on the website's licence or terms of use.
Examiner tip: Plagiarism is an issue of honesty and originality; copyright is a separate, legal issue about ownership of the content itself.
9.
Distinguish between a Local Area Network (LAN) and a Wide Area Network (WAN).
[2 marks] · no calculator
Marking points
- Explains that a LAN covers a small geographical area, such as a single building or school site.
- Explains that a WAN covers a much larger geographical area, often connecting multiple LANs across different cities or countries, typically using third-party infrastructure.
Examiner tip: The internet itself is the largest example of a WAN, connecting countless smaller networks together.
10.
Distinguish between a client-server network and a peer-to-peer network.
[2 marks] · no calculator
Marking points
- Explains that in a client-server network, a central server provides resources or services to multiple client devices that request them.
- Explains that in a peer-to-peer network, each device has equal status and can share resources directly with others, without a dedicated central server.
Examiner tip: A client-server network is easier to manage and secure centrally; a peer-to-peer network has no single point of failure but is harder to control centrally.
11.
Explain the purpose of an IP address on a network.
[1 mark] · no calculator
Marking points
- Explains that an IP address uniquely identifies a device on a network, allowing data to be correctly routed to and from it.
Examiner tip: An IP address is like a postal address for a device, letting data sent across a network know exactly where to be delivered.
12.
Distinguish between an IP address and a MAC address.
[2 marks] · no calculator
Marking points
- Explains that an IP address is assigned to a device by a network and can change depending on which network it connects to.
- Explains that a MAC address is a unique, permanent identifier physically assigned to a device's network hardware by its manufacturer, and does not change.
Examiner tip: Think of a MAC address as permanently built into the hardware, while an IP address is assigned temporarily depending on the network the device joins.
13.
Explain the function of a router in a home network.
[2 marks] · no calculator
Marking points
- Explains that a router directs (routes) data packets between different networks, such as between a home network and the wider internet.
- Explains that it uses IP addresses to determine the correct path to send each packet of data.
Examiner tip: A router connects separate networks together and decides where to send each packet of data; a switch, by contrast, connects devices within a single network.
14.
Explain how a firewall helps protect a network from unauthorised access.
[2 marks] · no calculator
Marking points
- Explains that a firewall monitors incoming and outgoing network traffic, checking it against a set of security rules.
- Explains that it blocks traffic that does not meet these rules, preventing unauthorised access from outside the network.
Examiner tip: A firewall acts as a filter at the boundary of a network, deciding what traffic is allowed in or out based on defined rules.
15.
Explain why an employee working from home might use a Virtual Private Network (VPN) to connect to their company's systems.
[2 marks] · no calculator
Marking points
- Explains that a VPN creates an encrypted connection (a secure 'tunnel') over the public internet.
- Explains that this protects sensitive company data from being intercepted and read by someone else on the public network.
Examiner tip: A VPN makes a connection over the public internet behave as securely as if the device were directly connected to the company's own private network.
16.
Explain what happens during a distributed denial-of-service (DDoS) attack.
[2 marks] · no calculator
Marking points
- Explains that a DDoS attack floods a server or website with an overwhelming number of requests from many different sources at once.
- Explains that this overwhelms the server's capacity, making the website slow or completely unavailable to genuine users.
Examiner tip: A DDoS attack does not try to steal data directly — its goal is to disrupt a service by exhausting its capacity to respond.
17.
Explain what is meant by a brute force attack on a password, and state one way a system can defend against it.
[2 marks] · no calculator
Marking points
- Explains that a brute force attack systematically tries every possible combination of characters until the correct password is found.
- States a valid defence, such as locking an account after a small number of failed attempts, or requiring long, complex passwords that take far longer to guess.
Examiner tip: Account lockouts and rate limits make brute force attacks impractically slow, even though the method itself is simple.
18.
Explain the difference between spyware and the other types of malware you have studied, in terms of its main purpose.
[2 marks] · no calculator
Marking points
- Explains that spyware's main purpose is to secretly monitor and collect information about a user's activity, such as keystrokes or browsing habits, without their knowledge.
- Contrasts this with malware designed mainly to spread and cause damage (such as a virus or worm), rather than to quietly gather information.
Examiner tip: Spyware's goal is covert information-gathering, which is a different objective from malware designed mainly to damage or disrupt a system.
19.
Explain one advantage of using biometric authentication, such as a fingerprint scan, instead of a traditional password.
[2 marks] · no calculator
Marking points
- States an advantage such as a fingerprint being unique to the user and impossible to forget, unlike a password.
- Explains that this also makes it harder for someone else to guess or steal, compared with a weak or reused password.
Examiner tip: Biometric data is based on a unique physical characteristic, so it cannot be forgotten and is much harder to guess than a typical password.
20.
Explain how two-factor authentication improves account security compared with using a password alone.
[2 marks] · no calculator
Marking points
- Explains that two-factor authentication requires a second, separate piece of evidence in addition to the password, such as a one-time code sent to the user's phone.
- Explains that even if an attacker discovers the password, they still cannot log in without also having access to the second factor.
Examiner tip: Two-factor authentication means a stolen password alone is no longer enough for an attacker to access the account.
21.
Explain what cookies are, and give one reason a website might use them.
[2 marks] · no calculator
Marking points
- Explains that cookies are small text files stored on a user's device by a website, to be read again on later visits.
- States a valid reason for their use, such as remembering login details, items in a shopping cart, or user preferences.
Examiner tip: Cookies let a website 'remember' a user between visits, since the web itself has no memory of previous requests on its own.
22.
Explain what is meant by bandwidth, and how it affects a user's experience when streaming video online.
[2 marks] · no calculator
Marking points
- Explains that bandwidth is the maximum amount of data that can be transferred over a network connection in a given amount of time.
- Explains that low bandwidth can cause streamed video to buffer, lag, or play at a lower quality, since data cannot arrive fast enough.
Examiner tip: Higher bandwidth allows more data to flow per second, which is essential for smooth high-quality video streaming.
23.
Explain the purpose of a digital certificate issued by a trusted certificate authority when you connect to a secure website.
[2 marks] · no calculator
Marking points
- Explains that the certificate verifies the identity of the website, confirming you are connecting to the genuine site and not an imposter.
- Explains that it also enables the encrypted (HTTPS) connection between the browser and the server.
Examiner tip: A certificate authority is a trusted third party that vouches for a website's identity, which is why browsers trust the padlock it enables.
24.
Explain what is meant by social engineering in a cybersecurity context, using an example other than a phishing email.
[2 marks] · no calculator
Marking points
- Explains that social engineering means manipulating or deceiving a person, rather than attacking a computer system directly, to gain unauthorised access or information.
- Gives a valid example other than phishing, such as someone pretending to be IT support over the phone to ask for a password, or watching over someone's shoulder to see them type a PIN.
Examiner tip: Social engineering exploits human trust and behaviour rather than a technical weakness in the computer system itself.