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 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:

• A LAN covers a small geographical area (1) because all the charity's computers are in one building/on one site (1)
• The charity can use its own cabling/equipment (1) so it does not need to rent leased lines from a telecoms provider (1)
• The charity owns the infrastructure (1) so it avoids the cost of leased lines/external connections that a WAN needs (1)
• The devices are close together (1) so the LAN can use short, high-speed cabling (1)

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

Do not accept 'it is faster/better/cheaper' on its own without a linked reason (e.g. short distance, own cabling, no leased lines).

Allow 'the LAN is private/secure' only with a linked reason such as the charity controls its own equipment.

Do not accept 'a LAN is local' or 'a WAN is too far/expensive' without a linked reason about the small area or leased lines.

Do not accept 'the computers are in one building/on one site' on its own because it repeats the stem; it must be linked to a reason such as a LAN covering a small geographical area.

Do not accept 'stronger Wi-Fi/signal' as a reason.

Do not accept 'can share files/printers' on its own because this is a reason for any network, not for choosing a LAN over a WAN.