Lesson 4.9.4.1

4.9.4.1 TCP/IP Quiz: AQA Computer Science, Unit 9

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.9.4.1, TCP/IP: 20 multiple choice questions for the AQA Computer Science (7517), Unit 9: Fundamentals of communication and networking, written with Revision Ninja.

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The 20 questions

  1. What are the four layers of the TCP/IP stack?

    • Application, transport, network and link
    • Hardware, driver, kernel and user
    • Physical, data link, network and session
    • Presentation, session, transport and application

  2. Which layer is responsible for routing packets across networks?

    • The link layer
    • The network layer
    • The transport layer
    • The application layer

  3. Which layer handles end-to-end delivery and the ports used by applications?

    • The network layer, which routes packets between different networks
    • The link layer, which handles the frames sent on the physical cable
    • The application layer, which turns user data into a file format
    • The transport layer

  4. What does the link layer handle?

    • Translating domain names into IP addresses for the browser to use, by querying the DNS servers on the path
    • Providing protocols such as HTTP that applications use to exchange their data, with each request and response
    • Transmission over a single physical link, using MAC addresses to deliver frames to devices on the same network
    • Routing packets across the Internet using IP addresses between many networks, choosing the route for each packet

  5. What is a socket in the TCP/IP stack?

    • An endpoint for communication, identified by an IP address and a port number, used by a program
    • A file that stores the routing table for a router on the Internet, which is updated as the routes change
    • A physical connector on the back of a computer for a network cable, which holds the cable in place firmly
    • A hardware component that stores the MAC address of a network adapter, so that the address is kept safe

  6. What is the role of a MAC address?

    • A logical address that routers use to route packets between different networks
    • A domain name that is registered with an Internet registry for public use
    • A hardware address that identifies a network interface on the same local network
    • A port number that a server uses to listen for incoming web requests

  7. What are well-known ports used for?

    • Temporary ports that a client's operating system picks for each outgoing connection
    • Ports used only for wireless networking between devices in a home
    • Standard services that servers listen on, such as port 80 for HTTP and port 443 for HTTPS
    • Ports reserved for the MAC addresses of the router on the local network

  8. How do client ports differ from well-known ports?

    • Client ports are fixed for standard services, while well-known ports are chosen at random for each connection
    • Client ports are used only for email, while well-known ports are used only for file transfer
    • Client ports and well-known ports are always the same number on the same machine
    • Client ports are temporary numbers chosen for each connection, while well-known ports are fixed for standard services

  9. A browser connects to a server on port 80 from its own client port 49152. Which port is the well-known one?

    • Port 49152
    • Both ports are well-known ports for the same service
    • Neither port is well-known, because each is used for a single connection only
    • Port 80

  10. Which protocol does a browser use to request a web page?

    • HTTP, or HTTPS for a secure connection
    • SMTP, which sends email between servers
    • FTP, which transfers files with anonymous or non-anonymous access
    • POP3, which retrieves email from a mail server

  11. A user's email is sent using SMTP. Which protocol is used to retrieve it later from the mail server?

    • FTP
    • POP3
    • SSH
    • HTTPS

  12. How does an SSH client make use of a TCP connection to a remote port?

    • It asks the DNS system for the IP address of the remote host and then stops
    • It sends the connection request over the link layer only, without using any port number
    • It encrypts each packet using a MAC address before it leaves the local network
    • It connects to the remote port and sends application commands, such as GET for HTTP, over the connection

  13. What is the role of an email server?

    • To store the web pages that the browser of each user requests
    • To send and retrieve email on behalf of users
    • To translate domain names into IP addresses for every device
    • To assign IP addresses to devices when they join a local network

  14. What does a web browser do with the web page resources it retrieves?

    • It converts the page into bytecode so that it can run on a virtual machine
    • It stores the page only on the server and never displays it on the local device
    • It sends the page to the DNS server for translation into an IP address
    • It retrieves the page and its resources, such as images, and renders them accordingly

  15. Which application-layer protocol is used for secure remote management and logging in to a remote computer?

    • POP3
    • SSH
    • SMTP
    • HTTP

  16. A TCP/IP stack has four layers. When an application sends a message, through how many layers does the data pass on its way down the stack?

    • Three
    • Five
    • Four
    • Two

  17. Why does a socket need both an IP address and a port number?

    • The IP address identifies the host, and the port identifies the particular program or service on that host
    • The port number is a MAC address and the IP address is a domain name
    • The IP address identifies the program, and the port identifies the host on which it runs
    • Both identify the cable used to reach the host, so both are needed to route packets

  18. A server responds to requests on port 443. Which description is correct?

    • Port 443 is reserved for the MAC address of its network card, so it cannot serve requests
    • It responds only to email, because port 443 is used by SMTP for all messages
    • It uses a client port that changes for each request, which is why clients cannot find it
    • It uses the well-known port for HTTPS, so clients can connect to it using the standard port

  19. A packet is sent between two devices on the same local network using their hardware addresses. Which layer uses these addresses?

    • The link layer
    • The transport layer
    • The application layer
    • The network layer

  20. When an application message is sent through the TCP/IP stack, what happens to the data at each layer?

    • Each layer adds its own header as the data passes down, and the receiver removes the headers on the way up
    • Only the application layer adds headers, and the lower layers simply forward the data unchanged
    • Each layer removes the data and passes only its header down to the next layer
    • The data passes through the link layer first and is then discarded by the application layer

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