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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 659 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 · 5 marks

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1Short recall1 markAddressing Swap Remove

An IPv4 address is made up of four 8-bit numbers separated by dots.

State the range of values that each number in an IPv4 address can have.

[1 mark]
Mark scheme

Award one mark for:

  • 0 to 255 (1)

Allow 0–255 / 0-255 / between 0 and 255 / 0 and 255.

Do not accept 1 to 255 (0 is a valid value).

Do not accept any range that includes 256, e.g. 0 to 256.

Example answers and how they were marked
Full marks1/1

0 to 255

Why: Gives the correct range (1).

No marks0/1

1 to 255

Why: Near miss: excludes 0, which is a valid value; the Do not accept line applies.

No marks0/1

0 to 256

Why: Includes 256, which is not valid; the Do not accept line applies.

2Explain2 marksProtocols & Layers Swap Remove

The TCP/IP model has four layers.

Explain one function of the transport layer when a file is sent over a network.

[2 marks]
Mark scheme

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

  • Splits the data/file into packets (1) so each packet can be sent separately across the network (1)
  • Adds a packet/sequence number to each packet (1) so the packets can be put back into the correct order at the destination (1)
  • Detects lost/missing packets (1) so they can be requested/resent (1)
  • Creates a connection between the two computers/hosts (1) before the file is sent (1)

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

Allow 'segments' for 'packets' (TCP divides the data into segments, which become packets at the internet layer).

Do not accept 'sends the data/file' on its own without saying what the transport layer does to the data.

Do not accept naming TCP or a port number on its own without expansion.

Do not accept routing/addressing packets using IP addresses, which is the internet layer.

Example answers and how they were marked
Full marks2/2

The transport layer splits the data into packets so each packet can be sent separately across the network.

Why: Linked point (1) and reason (1): splitting into packets lets each one be sent separately.

Some marks1/2

It splits the data into packets.

Why: Point (1) identified, but no linked reason given, so only the first mark is awarded.

No marks0/2

It routes the packets using IP addresses so they reach the right destination.

Why: Routing using IP addresses is the internet layer, not the transport layer, so no credit is given.

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.

Questions by topic

5.3 Cybersecurity

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