Edexcel GCSE Computer Science (1CP2) Exam Questions

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.

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 offices are a large distance apart/in different countries (1) so a WAN connects the separate networks over a large geographical area (1)
• A WAN connects two or more LANs together (1) so the separate office networks can communicate (1)
• A WAN can use leased lines rented from telecommunications companies (1) because the company does not own the long-distance cabling between countries (1)

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

Allow 'a WAN covers a large geographical area' as the WAN feature (1) when linked to the company's offices being in different countries/cities (1).

Allow leased lines rented from telecommunications companies as the WAN feature (1) if linked to the company not owning the long-distance cabling (1).

Do not accept 'a WAN is bigger/faster' without saying that it connects networks over a large distance.

Do not accept 'the offices are in different countries' on its own as a linked explanation, because it does not state a WAN feature.

Do not accept 'WAN covers a large area' on its own without linking it to the company's offices.

Do not accept 'the internet is a WAN' on its own.

Do not accept 'more secure/safer' on its own because this does not explain the need to connect distant offices.