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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

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

Two computers exchange data over a network.

Explain why network protocols are needed for the two computers to communicate.

[2 marks]
Mark scheme

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

  • Devices (can) understand/interpret the data they receive (1) because they follow the same set of rules for communication (1)
  • Data is sent in an agreed format/structure (1) so the receiving device can interpret/understand it correctly (1)
  • Devices (can) connect/communicate successfully (1) because they agree how the data is transmitted, such as the type of signal used (1)
  • Errors (can) be detected/handled (1) because both devices follow the same rules for checking the data (1)

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

Do not accept 'so devices can talk/communicate with each other' or 'so they can understand each other' without saying they follow the same rules/agreed format.

Do not accept an answer that only states protocols are a set of rules, without saying what this allows (e.g. the data can be understood/interpreted).

Do not accept a faster connection/speed as a reason why protocols are needed.

Do not accept naming a protocol (e.g. TCP/IP, HTTP, Wi-Fi) without an explanation of why it is needed.

Do not accept a description of what a protocol does (e.g. 'TCP splits data into packets') without saying why this is needed.

Example answers and how they were marked
Full marks2/2

Devices can understand the data they receive because they follow the same set of rules for communication.

Why: Linked point (1) and reason (1): following the same rules is what lets the devices understand the data.

Some marks1/2

Data is sent in an agreed format.

Why: Point (1) identified, but no linked reason saying what the agreed format achieves.

No marks0/2

Protocols are needed so the connection is faster because more data can be sent at once.

Why: Speed is not a reason protocols are needed, so there is no creditworthy point or linked reason.

3Explain2 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.

4Explain2 marksWireless Connections Swap Remove

A student plays an online game using a laptop connected to the school Wi-Fi.

Explain one reason why an online game can respond more slowly over a wireless connection than over a wired connection.

[2 marks]
Mark scheme

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

  • Wireless signals can be blocked or absorbed by walls (1) so the data must be re-sent, which adds delay (1)
  • A device further from the access point has a weaker signal (1) so data must be re-sent/transmitted at a lower rate, adding delay (1)
  • Devices on a wireless network share a channel (1) so a device must wait its turn to transmit, which adds delay (1)
  • Interference from other devices affects the radio signal (1) so data must be re-sent, adding delay (1)

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

Allow 'waiting to send' or 'collisions' as the delay caused by devices sharing a channel.

Do not accept 'wireless is slower than wired' on its own, as this repeats the question.

Do not accept a reason that only affects download speed/bandwidth (e.g. 'files take longer to download') without a link to delay.

Example answers and how they were marked
Full marks2/2

Interference from other devices affects the radio signal, so the data has to be re-sent and this adds delay before the player's action appears.

Why: Linked point (1): interference affects the signal; reason (1): re-sending the data adds delay (latency).

Some marks1/2

Walls can block the wireless signal.

Why: Point only (1): walls block the signal. No linked reason saying that this means data must be re-sent, which adds delay.

No marks0/2

Wireless has less bandwidth than wired, so a game update takes longer to download.

Why: Confuses latency with bandwidth/download speed; the mark scheme says not to accept this without a link to delay.

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