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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 · 5 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 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 marksThe Internet Swap Remove

Routers on the internet choose a route for each packet.

Explain one benefit of a router being able to choose a different route for a packet.

[2 marks]
Mark scheme

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

  • Data can avoid a busy/congested link (1) because the router can choose another path (1)
  • Data can still arrive if a link fails (1) because the router sends it another way (1)
  • Data can take the shortest/fastest path (1) because the router compares the routes and chooses the one with the fewest hops/least traffic (1)

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

Allow other valid benefits with a linked reason, e.g. traffic can be shared across routes/load balanced (1) because the router can send some packets by another path (1)

Do not accept 'the route is always the same' as this is not a benefit of choosing a route.

Do not accept 'routers are fast' or 'packets are sent faster' on its own: the reason must say how the route is chosen, e.g. avoiding congestion or using a routing table.

Example answers and how they were marked
Full marks2/2

If one route is busy, the data can still get there because the router can choose a different path.

Why: Linked point (1) and reason (1): a different path avoids the busy route.

Some marks1/2

It can choose the fastest route because routers are quick.

Why: Point (1) for choosing the fastest route, but 'routers are quick' is a speed statement that does not say how the route is chosen, so it does not earn the second mark.

No marks0/2

It means more devices can connect to the internet.

Why: No link to choosing a route for a packet; does not answer the question.

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