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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 693 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.

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3 questions · 6 marks

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1Describe2 marksWireless Connections Swap Remove

A network can use wired connections or wireless connections.

Describe why a wireless connection can have a higher latency than a wired connection.

[2 marks]
Mark scheme

Award up to two marks for a linked description such as:

  • Interference from other devices corrupts the wireless signal (1) so the data has to be resent, which increases the delay (1)
  • Devices on a wireless network take turns to use the same channel/frequency (1) so a device may have to wait for the channel to be free before it can transmit, which adds to the delay (1)
  • Data on a wireless connection must pass through the access point to reach the wired network (1) so the extra processing/conversion at the access point adds a delay (1)

Do not accept responses that only state that a wireless connection is slower/less reliable than a wired connection, without explaining how this adds latency.

Do not accept 'data is sent through the air' on its own, as this does not explain why latency is higher.

Do not accept responses about bandwidth or speed on their own.

Example answers and how they were marked
Full marks2/2

Interference from other devices can corrupt the wireless signal, so the data has to be resent, which increases the delay.

Why: Linked point: interference corrupts the signal (1), developed by the delay caused by resending the data (1).

Some marks1/2

Wireless signals can be corrupted by interference from other devices.

Why: The point that interference corrupts the wireless signal (1) is given, but there is no development of how this leads to a delay.

No marks0/2

Wireless is slower than a wired connection, so it has a higher latency.

Why: Only states that wireless is slower, without explaining how this adds latency, so it is not accepted.

2Describe2 marksWireless Connections Swap Remove

An office has one wireless access point that employees connect their laptops to.

Describe how connecting more devices to the wireless access point can affect the speed and latency of the network.

[2 marks]
Mark scheme

Award up to two marks for a linked description such as:

  • The bandwidth/capacity of the access point is shared between all the connected devices (1) so each device gets less bandwidth as more devices connect, which reduces the speed of data transfer (1)
  • The devices have to take turns to transmit (contention) (1) so each device waits longer before it can send data, which increases latency (1)
  • The access point can only support a maximum number of connections (1) so once this limit is reached, further devices cannot connect to the network (1)

Allow 'contention' as an alternative to devices having to take turns to transmit.

Allow 'the network becomes slower' as the second mark only where it is linked to shared bandwidth, to devices taking turns to transmit or to the maximum number of connections.

Do not accept a response that only states the network becomes slower, or that there are more devices/more traffic, without saying how this affects performance.

Do not accept responses about range or interference unless they are linked to the number of connected devices.

Example answers and how they were marked
Full marks2/2

All of the connected devices share the bandwidth of the access point, so as more devices are added each device gets less bandwidth and data is transferred more slowly.

Why: Shared bandwidth point (1) developed into the effect on the speed of data transfer (1).

Some marks1/2

The bandwidth of the access point has to be shared between all the devices that are connected to it.

Why: Correct point that bandwidth is shared (1), but there is no development saying how this affects the speed or latency, so only one mark.

No marks0/2

Each device gets its own bandwidth from the access point, so adding more devices does not change the speed.

Why: Misconception that bandwidth is not shared, so no creditworthy point is made.

3Explain2 marksThe Internet Swap Remove

Each data packet has a header that contains the destination IP address.

Explain one reason why a data packet contains the destination IP address.

[2 marks]
Mark scheme

Award up to two marks for a linked explanation such as:

  • Routers can forward the packet towards its destination (1) because they read the destination IP address in the packet header (1)
  • The packet is delivered to the correct device (1) because the receiving device compares the destination IP address with its own IP address (1)
  • Each packet can take a different route (1) because routers use the destination IP address to choose the next router (1)
  • The packet can be passed on by each router in turn (1) because the destination IP address shows which network the packet is for (1)

For both marks, the expansion must follow/associate with the statement.

Statements such as 'so it reaches the right destination' or 'so routers know where to send it' earn the first mark only; do not award the second mark unless the reason says that the address is read from the packet header and used to forward the packet.

Do not accept 'so it knows where it came from' as this describes the source address, not the destination address.

Do not accept 'so it gets there faster' without a linked reason.

Example answers and how they were marked
Full marks2/2

Routers know where to send it because they use the address in the packet header to choose the next network.

Why: Linked point (1) and reason (1): routers read the destination IP address in the header to forward the packet.

Some marks1/2

So that it reaches the right destination because every packet has an address.

Why: First mark (1) for reaching the right destination, but the reason is circular and does not say the address is read and used to forward the packet.

No marks0/2

So the packet knows where it came from.

Why: Describes the source address, not the destination address; do not accept.

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