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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 631 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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4 questions · 6 marks

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1Multiple choice1 markPacket Switching Swap Remove

Identify what a router does with a data packet it receives.

[1 mark]
  • AGives the packet a number
  • BSends it on to the next router
  • CPuts the packets into order
  • DRebuilds the original file
Mark scheme
  • B Sends it on to the next router (1)
  • The only correct answer is B. The correct answer is sends it on to the next router.
  • A is not correct because a packet is given its number by the sending computer before it is sent
  • C is not correct because packets are put back into order by the receiving computer
  • D is not correct because the original file is rebuilt by the receiving computer once all the packets arrive
Example answers and how they were marked
Full marks1/1

B Sends it on to the next router

Why: Selected the action a router performs on a packet it receives (1).

No marks0/1

D Rebuilds the original file

Why: A near miss: rebuilding the file is a packet switching action, but it is done by the receiving computer, not by a router.

No marks0/1

A Gives the packet a number

Why: Misconception: packets are numbered by the sending computer, so a router does not add a packet number.

2Short 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.

3Short recall2 marksWireless Connections Swap Remove

Latency affects the performance of a network.

Define the term latency.

[2 marks]
Mark scheme

Award one mark for any of the following up to a maximum of two marks:

  • A delay/time/lag (1)
  • Between a signal/request being sent and a response/data being received (1)

Allow 'the time taken for data to travel from source to destination' for both marks.

Do not accept 'the speed at which data travels' / 'bandwidth' / 'the amount of data sent per second'.

Example answers and how they were marked
Full marks2/2

The delay between a signal being sent and a response being received.

Why: Gives the delay (1) and the time between sending and receiving (1).

Some marks1/2

The time taken for data to travel.

Why: Gives the idea of time taken (1) but does not say between sending and receiving (1).

No marks0/2

The speed at which data is sent over the network.

Why: Describes speed, not latency; no creditworthy point.

4Explain2 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'.

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