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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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4 questions · 7 marks

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1Short recall1 markAddressing Swap Remove

Routers forward data packets across the internet.

State the part of a data packet that a router uses to decide where to send it.

[1 mark]
Mark scheme

Award one mark for:

  • (Destination) IP address (1)

Allow IP address on its own (the destination is implied).

Do not accept source IP address/IP address of the sender.

Do not accept MAC address.

Do not accept domain name/web address.

Example answers and how they were marked
Full marks1/1

The destination IP address.

Why: Names the destination IP address (1).

No marks0/1

The domain name.

Why: A domain name is not used by a router to route a packet; it must be translated to an IP address first, so no mark.

No marks0/1

The MAC address.

Why: A MAC address is not used to route packets across the internet; the Do not accept line applies.

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 marksThe Internet Swap Remove

Every device that connects to the internet is given an IP address.

Explain one reason why every device on the internet needs a unique IP address.

[2 marks]
Mark scheme

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

  • Data/packets are delivered to the correct device (1) because the IP address identifies that device on the internet (1)
  • A reply is sent back to the device that made a request (1) because the sender's IP address is used as the destination address for the reply (1)
  • Routers can forward packets to the right device (1) because each packet's destination IP address matches only one device (1)
  • A device can be contacted by other devices (1) because other devices use its IP address to send data to it (1)

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

Allow 'so the router knows where to send data' only when expanded to say the IP address identifies the destination device / is used by routers to forward the packet to that device.

Do not accept 'so it can connect to the internet' / 'so it can access the internet' without saying how the address is used to identify the device or deliver data to it.

Do not accept 'so the device can be identified' on its own without saying what the identification is used for, e.g. delivering data or returning a reply.

Do not award a mark for restating that an IP address is unique / every device has a different address.

Example answers and how they were marked
Full marks2/2

So that data reaches the correct device. The IP address is how the internet tells one device apart from another, so packets are sent to that device and not to a different one.

Why: Point (1): data reaches the correct device. Reason (1): the IP address identifies/tells devices apart, so packets are sent to that device.

Some marks1/2

So that packets go to the right device, because every device has a different address.

Why: Point (1): packets go to the right device. The reason only restates that every device has a different address, which the mark scheme says does not earn the second mark.

No marks0/2

So it can connect to the internet.

Why: No linked explanation of how the address is used; 'so it can connect to the internet' is not accepted without expansion.

4Explain2 marksAddressing Swap Remove

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

Explain why each device that receives packets over the internet needs a unique IP address.

[2 marks]
Mark scheme

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

  • Data/packets are delivered to the correct/intended device (1) because the destination IP address identifies that device, so a duplicate address would mean packets could be delivered to the wrong device (1)
  • Replies are sent back to the device that requested the data (1) because the sender's IP address identifies that device, so a duplicate address would mean the reply could be sent to the wrong device (1)
  • The device can be identified separately from other devices (1) so packets are not delivered to a different device that has the same address (1)

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

Award one mark for a valid point and a second mark only for a linked reason explaining why a duplicate address would cause a problem.

Do not accept 'it is unique'/'it has its own address' as a point, as this repeats the question.

Do not accept 'so it can connect to the internet' or 'so it can be found' on its own without a link to data/packets being delivered to the correct device.

Allow 'data' for 'packets'.

Example answers and how they were marked
Full marks2/2

Packets are delivered to the correct device because the destination IP address identifies one device, so if two devices had the same address packets could be sent to the wrong one.

Why: Point that packets reach the correct device (1) and linked reason that a duplicate address would cause misdelivery (1).

Some marks1/2

Packets are sent to the correct device because it has its own IP address.

Why: Valid point that packets reach the correct device (1), but the reason only restates uniqueness and does not explain how a duplicate address would cause a problem, so no second mark.

No marks0/2

So that it can connect to the internet.

Why: No link to packets/data being delivered to the correct device; the mark scheme rejects a connection statement on its own.

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