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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 · 8 marks

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1Short 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.

2Describe2 marksWired Connections Swap Remove

A hospital connects the computers on a ward using wired connections.

Describe how using wired connections can reduce latency on this network.

[2 marks]
Mark scheme

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

  • Data travels along the cable directly to the switch on a single continuous path (1) so the time between sending and receiving the data is short (1)
  • A cable is not affected by interference from other devices/wireless traffic nearby (1) so packets are not lost and resent, which would add to the delay (1)
  • The switch sends the data only to the port of the correct device, not to every device (1) so the data spends less time travelling and the delay is lower (1)
  • Fewer devices share a cable than share a wireless channel (1) so packets do not queue/wait before they are sent (1)

The first mark is for the way the wired connection carries the data; the second mark is for how this reduces the delay between sending and receiving.

Do not accept responses about bandwidth or the amount of data a cable can carry, as latency is the delay between sending and receiving.

Do not accept responses that confuse latency with speed/bandwidth, e.g. 'a wired connection is faster so there is less latency', unless they describe how the delay is reduced.

Do not accept answers that only say a wired connection is faster, with no link to the delay.

Example answers and how they were marked
Full marks2/2

The cable is not affected by interference from other devices (1) so packets do not need to be resent and the delay stays low (1).

Why: First mark for the cable being free of interference (1); linked development that no packets are resent and so the delay is lower (1).

Some marks1/2

There is no interference from other devices on a cable.

Why: Gives the first point of a linked pair (1) but does not say how this reduces the delay between sending and receiving.

No marks0/2

Wired connections have a higher bandwidth so there is less latency.

Why: Confuses bandwidth with latency, which the 'Do not accept' lines rule out (0).

3Explain2 marksPacket Switching Swap Remove

A router connects a home network to the internet.

Explain how a router uses the destination IP address in a packet header.

[2 marks]
Mark scheme

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

  • The router reads the destination IP address (1) so it knows which network/device the packet is for (1)
  • The router looks up the destination IP address in its routing table (1) to find the next router/route for the packet (1)
  • The router forwards the packet to the next router (1) that leads towards that IP address / is on the best route (1)

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

Do not accept MAC address - routers use the IP address to route packets between networks.

Do not accept 'it finds the exact device' without saying how the router uses the address, e.g. routing table/next router.

Example answers and how they were marked
Full marks2/2

The router looks up the destination IP address in its routing table to find the next router to send the packet to.

Why: Linked point (1) and reason (1): looks up the destination IP address in the routing table to find the next router.

Some marks1/2

It reads the destination IP address.

Why: Reads the destination IP address (1) but gives no linked reason about a routing table or next router.

No marks0/2

It reads the MAC address so it knows which computer sent the packet.

Why: Routers use the IP address to route packets, not the MAC address; no creditworthy point.

4Explain2 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.

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