4.9.2.1 Network topology Quiz: AQA Computer Science, Unit 9

The 20 questions

1. What is a physical star topology?

   • Each device is connected by its own cable to a central device, such as a switch
   • All devices share a single backbone cable with a terminator at each end
   • Each device is wired directly to every other device in the network
   • Each device connects to two neighbours in a closed loop of cables

2. What is a logical bus network topology?

   • All devices share one communication channel, and each device receives data addressed to it, regardless of the physical layout
   • Devices connect only through one central server, and never communicate directly with each other, so all traffic is relayed
   • Devices pass a token around a ring so that each one transmits in turn, with the token passed on after every frame sent
   • Each device has a dedicated point-to-point link to every other device on the network, so that no two devices share a cable

3. How can a physically star-wired network behave logically as a bus?

   • By using a bus protocol and appropriate switching in the central device, so the devices share one logical channel
   • By using a ring protocol in which a token passes from one device to the next around the network, one device at a time
   • By connecting every device to the router with its own separate wireless link, which removes the need for any cable
   • By removing the central device so that each cable connects directly to the next computer, forming one long shared line

4. Which statement describes a failure in a physical bus network?

   • A break in the single backbone cable can disable communication for every device on the bus
   • A failure of a central switch stops all communication across the bus network entirely
   • A break in one device's cable isolates only that device from the rest of the network
   • A failed device on a bus always stops the whole network from working at the same time

5. What is an advantage of a physical star topology over a physical bus?

   • It guarantees that data is never delayed, whatever the amount of traffic on the network
   • A fault in one device's cable affects only that device, not the rest of the network
   • It requires less cable in every case, since each device connects to the next device
   • It removes the need for any central device, which reduces the cost of hardware

6. What is the main disadvantage of a physical star topology?

   • Devices cannot reach the central device unless the bus is broken first
   • The central device is a single point of failure, and extra cable is needed for each device
   • Devices must share one cable with all the others, which causes frequent collisions
   • Devices have no unique address, so the central device cannot identify them

7. Which statement correctly differentiates physical and logical topology?

   • Logical topology describes the speed of the cables, while physical topology describes their length
   • Physical topology is how cables and devices are laid out, while logical topology is how data flows and is shared
   • Physical and logical topologies always describe the same layout and use the same name
   • Physical topology is how data flows, while logical topology is how the cables are laid out

8. Why might an office choose a star topology for its network?

   • It is easy to add or remove devices and to isolate faults, since each device has its own cable to the centre
   • It ensures every device receives every frame, regardless of the address it carries
   • It means only one device can be connected to the central device at any one time
   • It removes the need for any cabling, because data travels through the air between devices

9. A star network has 12 computers, each with its own cable to a switch. How many cables are needed for the computers, assuming one each?

   • 12
   • 24
   • 13
   • 11

10. Which network has a central device whose failure disables the whole network?

    • A peer-to-peer network in which no device is designated as a server
    • A physical star network, where the central device is the single point of failure
    • A wireless network with a backup access point available for use
    • A physical bus network with terminators at both ends of the backbone

11. What must be true for a star-wired network to act logically as a bus?

    • Each cable must be connected to a different central device for every single connection
    • The central device must forward data so that every connected device can receive it on a shared logical channel
    • Each device must pass a token in a ring rather than rely on the central device at all
    • Each device must have its own separate logical channel to every other device on the network

12. A small office wants to add a computer without disturbing the others. Which topology allows this most easily?

    • Bus, because the new device must break the backbone cable to be connected
    • Star, because the new device needs only its own cable to the central device
    • Bus, because the new device needs no cable at all to join the network
    • Ring, because the new device must be placed between two existing devices in the loop

13. Which statement about a logical bus topology is true?

    • Data sent by one device is received only by the central device, which relays it onwards
    • Data sent by one device is received by every device, but only the addressed device processes it
    • Data passes from device to device in turn, with each device removing its own data
    • Every device has a private channel to every other device on the network at all times

14. A physical star network has 8 computers. One switch port fails. How many computers are affected?

    • None, because a star network has no single points of failure at all
    • All eight, because the star depends on every connection to work at all
    • Seven, because the switch serves all of the other devices on the network
    • One, the computer connected to that port

15. Which device is typically at the centre of a physical star topology in a home or office network?

    • A switch or router
    • A printer that receives all of the data sent across the network
    • A monitor that is connected to every computer on the network
    • A hard disk drive that stores files shared by everyone on the network

16. Which is a disadvantage of a bus topology?

    • Adding a device requires a new central device for every bus segment, so each extension needs extra hardware to join
    • It requires a separate cable from every device to a central switch, which makes the cabling far more expensive overall
    • All devices share one medium, so traffic from many devices must compete for the same channel
    • A break anywhere in the bus is isolated to a single device only, so the rest of the network carries on working normally

17. Compare star and bus when a single end device fails. Which statement is correct?

    • A failed end device stops both topologies, since every device is essential to the network and the others depend on it
    • A failed end device has no effect on either topology, because each one uses redundant cables that route around any fault
    • A failed end device disconnects only itself in either topology, but a failed central device stops a star network entirely
    • A failed end device stops a bus, but a star keeps working with no central device at all, because the cables are separate

18. A switch has 24 ports and 20 computers are connected. How many ports are free?

    • 2
    • 24
    • 20
    • 4

19. Why does a star topology make fault finding easier than a bus?

    • Each device shares a common cable, so faults can be located only from the central device
    • The bus topology uses a token that reports faults to one device on the network
    • Each device has its own cable to the centre, so a fault can be traced to a single link
    • The star uses no cables at all, so faults occur only in the memory of the switch

20. Which pairing describes a physical topology and its logical behaviour, as set out in the spec?

    • A physical ring that behaves logically as a mesh of point-to-point links
    • A physical star-wired network that behaves logically as a bus
    • A physical mesh that behaves logically as a single shared bus cable
    • A physical bus that behaves logically as a star with a central switch

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