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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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3 questions · 6 marks

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1Explain2 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.

2Explain2 marksThe Internet Swap Remove

Each data packet has a header that contains the destination IP address.

Explain one reason why a data packet contains the destination IP address.

[2 marks]
Mark scheme

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

  • Routers can forward the packet towards its destination (1) because they read the destination IP address in the packet header (1)
  • The packet is delivered to the correct device (1) because the receiving device compares the destination IP address with its own IP address (1)
  • Each packet can take a different route (1) because routers use the destination IP address to choose the next router (1)
  • The packet can be passed on by each router in turn (1) because the destination IP address shows which network the packet is for (1)

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

Statements such as 'so it reaches the right destination' or 'so routers know where to send it' earn the first mark only; do not award the second mark unless the reason says that the address is read from the packet header and used to forward the packet.

Do not accept 'so it knows where it came from' as this describes the source address, not the destination address.

Do not accept 'so it gets there faster' without a linked reason.

Example answers and how they were marked
Full marks2/2

Routers know where to send it because they use the address in the packet header to choose the next network.

Why: Linked point (1) and reason (1): routers read the destination IP address in the header to forward the packet.

Some marks1/2

So that it reaches the right destination because every packet has an address.

Why: First mark (1) for reaching the right destination, but the reason is circular and does not say the address is read and used to forward the packet.

No marks0/2

So the packet knows where it came from.

Why: Describes the source address, not the destination address; do not accept.

3Explain2 marksAddressing Swap Remove

Routers forward data across the internet.

Explain how a router uses the destination IP address of a packet to send the packet towards its destination.

[2 marks]
Mark scheme

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

  • The router reads/checks the destination (IP) address in the packet (1) so it can forward/send the packet towards that address/destination (1)
  • The router looks up/compares the destination (IP) address (1) to choose the route/next network/next router for the packet (1)
  • The router uses the destination (IP) address to choose/select the outgoing connection/network (1) so the packet is sent one step closer to its destination (1)

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

Do not accept a restatement of the question, such as 'the router uses the IP address to forward the packet', without saying how the address is used, e.g. checking the destination address or choosing the route/next network.

Do not accept answers that say the router gives/adds an IP address to the packet, or that the router uses a MAC address instead of the destination IP address.

Example answers and how they were marked
Full marks2/2

The router checks the destination IP address in the packet and sends the packet out on the route/network that leads towards that address.

Why: Point (1): the router checks the destination IP address; linked reason (1): this is used to send the packet towards that destination.

Some marks1/2

The router checks the destination IP address in the packet.

Why: Point (1): the router checks the destination IP address; no linked reason is given, so only the first mark.

No marks0/2

It adds an IP address to the packet so the packet knows where to go.

Why: Misconception: the router does not add an IP address to the packet; the mark scheme says not to accept this, so no marks.

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