Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• (Ethernet) cables are not affected by interference from other devices (1) so data is transferred at a consistent/steady speed (1)
• Each device has its own cable to the switch (1) so the full bandwidth is available to that device and speeds do not drop as more users join (1)
• Fibre optic cable has a higher bandwidth than a wireless link (1) so more data can be sent along the cable each second (1)
• The cable gives a direct/physical path to the switch (1) so data is less likely to be lost and resent, which would slow the transfer (1)

Do not accept responses about security, reliability or users being unable to move around, as these are not about speed.

Do not accept answers that only say a wired/cable connection is faster, or that fibre is faster, without saying why.

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

• (Twisted pair/copper) cable only carries data over a limited distance (about 100 metres) (1) so sensors further away need another switch/device to pass the data on to the farmhouse (1)
• Fibre optic cable can carry data over much longer distances (1) so wired connections can reach sensors across the whole farm (1)
• Data sent further than the cable's range is not received (1) so the computer in the farmhouse does not get readings from those sensors (1)
• A wireless connection can reach sensors that are out of range of the cables (1) so a mix of the two can give readings across the whole site (1)

Allow responses about signal weakening/being lost over a long cable.

Do not accept responses about bandwidth or speed, as range is about distance, not the amount or rate of data.

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.

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.