Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• Bandwidth is the maximum amount/capacity of data that can be carried each second (1) so a higher bandwidth lets editors open the large video files from the server in less time (1)
• The bandwidth of the cable is set by the type/standard of cable used (1) so it limits how much of a large file can be sent in a given time (1)
• A higher bandwidth means the cable can be shared between more transfers at the same time (1) so several editors can open files from the server at once without their transfers slowing down (1)
• If the bandwidth is too low for the size of the files (1) the transfers take a long time and the editors have to wait for their files to open (1)

Allow 'capacity' for 'maximum amount of data'.

A description that only defines bandwidth earns a maximum of one mark.

Do not accept responses about the time a signal takes to travel (latency) or the distance a signal can reach (range).

Do not accept answers that say bandwidth is how fast the signal/data travels along the cable, that a higher bandwidth gives a faster internet connection, or that bandwidth is the number of cables in the network.

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

• Each router chooses the best route at the time (1) so when a route becomes busy/congested or fails, later packets are forwarded along a different path (1)
• Routers forward each packet separately (1) so the path a packet takes depends on the traffic conditions when that packet arrives (1)
• A router may send a packet to a different next router (1) if its routing table shows a better/less congested route for that packet (1)
• Traffic on the internet changes (1) so no single path is kept for the file and each packet can use whichever route is best when it is sent (1)

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

Allow reference to a routing table, or to how a router decides the route, as part of the linked reason.

Do not accept 'the packets have different IP addresses' because all packets from the same file have the same destination IP address, even though their routes can differ.

Do not accept 'the internet is busy' or 'there is a lot of traffic' on its own without linking this to the router choosing a different route.

Do not accept 'different routers send the packets' on its own without a reason why a different router/route is chosen.

Do not accept an answer that only says the packets take different routes without explaining why.

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.