Menu

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.

Build a paper

Topics (none ticked: all of them)
Question types (none ticked: all of them)

Practice paper

3 questions · 5 marks

Pick again
Print
1Multiple choice1 markPacket Switching Swap Remove

Identify the purpose of the packet number in a data packet.

[1 mark]
  • ATo check the packet for errors
  • BTo identify the destination device
  • CTo reassemble the packets in the correct order
  • DTo select the fastest route for the packet
Mark scheme
  • C To reassemble the packets in the correct order (1)
  • The only correct answer is C. The correct answer is To reassemble the packets in the correct order.
  • A is not correct because error checking uses the error checking data in the packet, not the packet number
  • B is not correct because the destination IP address identifies the destination device, not the packet number
  • D is not correct because routers use the destination IP address to choose the route, not the packet number; routers may briefly buffer packets but do not use the packet number to store them
Example answers and how they were marked
Full marks1/1

C To reassemble the packets in the correct order

Why: Selected the purpose of the packet number, which allows the packets to be reassembled in the correct order (1).

No marks0/1

D To select the fastest route for the packet

Why: A near miss: routers choose routes using the destination IP address, so this does not describe the purpose of the packet number.

No marks0/1

B To identify the destination device

Why: Misconception: the destination IP address identifies the destination device, not the packet number.

2Short 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.

3Explain2 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'.

Questions by topic

More ways to revise Edexcel GCSE Computer Science (1CP2)

Teachers: build a paper, print it with the mark schemes at the end, and sign your school up to set your classes activities on every topic.

Fetch Decode Explain isn't affiliated with or endorsed by Pearson Edexcel.