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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 marksAddressing Swap Remove

A laptop is used at home and then taken on holiday.

Describe how the laptop's IP address can change.

[2 marks]
Mark scheme

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

  • The IP address belongs to the network/router the device is connected to (1) so a different network/router gives it a new address (1)
  • Home routers may use dynamic IP addresses (1) which can change when the router reconnects (1)
  • The ISP assigns the IP address (1) and may give a different one at a new location/connection (1)

Do not accept answers that only say the laptop has moved.

Do not accept the MAC address changes.

Example answers and how they were marked
Full marks2/2

The IP address is assigned by the router on the network it connects to, so when the laptop joins a different network on holiday it is given a new address.

Why: Linked point (1): IP address belongs to the connected network/router; development (1): a different network gives it a new address.

Some marks1/2

The IP address can change because it is dynamic.

Why: Point only (1): home routers may use dynamic IP addresses; the linked development about reconnecting is missing.

No marks0/2

The laptop's MAC address changes when it connects to a different network, so its IP address changes too.

Why: No creditworthy point: says the MAC address changes, which the mark scheme says not to accept.

2Explain2 marksPacket Switching Swap Remove

Data is split into packets before it is sent across the internet.

Explain why each packet has a packet number in its header.

[2 marks]
Mark scheme

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

  • The receiver can put the packets back into the correct order (1) because packets may arrive out of order/take different routes (1)
  • The receiver can see if a packet is missing (1) because the sequence of numbers shows a gap (1)
  • The receiver knows when the whole file has arrived (1) because the total number of packets/last packet number is known (1)

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

Allow 'so the packets can be put back in the correct order/reassembled' for the first mark, but the second mark needs the reason, i.e. packets may arrive out of order/take different routes.

Do not accept 'so the packets can be identified' without stating what the number is used for, e.g. reordering or spotting a missing packet.

Do not accept 'so the router knows where to send it' - the router uses the destination IP address, not the packet number.

Example answers and how they were marked
Full marks2/2

The receiver can put the packets back in the correct order because they may arrive out of order.

Why: Linked point (1) and reason (1): the packet number allows reordering because packets can arrive out of order.

Some marks1/2

It shows the receiver the order of the packets.

Why: The point is given (1) but there is no linked reason, such as packets arriving out of order.

No marks0/2

So the router knows which route to use.

Why: Routers use the destination IP address, not the packet number, so this earns nothing; it is named in the mark scheme as a 'Do not accept'.

3Explain2 marksWireless Connections Swap Remove

An office wireless network is near a microwave oven and several other wireless networks.

Explain how interference can affect the speed of a wireless network.

[2 marks]
Mark scheme

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

  • The speed of data transfer is reduced/is slower (1) because interference corrupts the radio signal, so data/packets are lost and have to be resent/retransmitted (1)
  • The network speed is lower (1) because there is more noise on the wireless signal, so data is sent at a lower transmission rate (1)
  • The throughput of the wireless network is reduced (1) because time is used resending corrupted data/packets instead of sending new data (1)

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

Award 1 mark for a statement that the speed/transfer rate is reduced (e.g. slower, takes longer), even if no reason is given.

Do not accept 'interference damages/corrupts the radio signal' or 'the signal is weaker' on its own without a link to the speed.

Do not accept 'data is lost' on its own without saying how this reduces the speed.

Do not accept 'interference increases the bandwidth' or 'interference makes the signal stronger'.

Example answers and how they were marked
Full marks2/2

Interference corrupts the radio signal, so packets are lost and resent, which makes the data transfer slower.

Why: Linked point (1): data transfer is slower; reason (1): interference corrupts the signal so packets are lost and resent.

Some marks1/2

The speed of the wireless network will be lower.

Why: Point only (1): states the effect on speed. No linked reason why interference causes this.

No marks0/2

Interference increases the bandwidth, so the data travels faster.

Why: Misconception that interference increases bandwidth; the mark scheme says not to accept this.

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