Edexcel GCSE Computer Science (1CP2) Exam Questions

• C Router (1)
• The only correct answer is C. The correct answer is router.
• A is not correct because a hub sends data to every device on the network
• B is not correct because a network interface card connects a device to a network
• D is not correct because a switch forwards data within a single network using MAC addresses

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:

• 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.

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

• Devices near the edge/limit of the range receive a weaker signal/lower signal strength (1) so data is transferred more slowly/the connection speed/bandwidth is lower (1)
• Devices near the edge/limit of the range receive a weaker signal/lower signal strength (1) so latency increases (1)
• Devices outside the range cannot connect to the access point (1) so users in that area cannot use the network/access its resources (1)
• A device that moves out of range loses its connection (1) so the user's work is interrupted until it is back in range (1)

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

For the second mark, the reason must state the effect on the user/network (e.g. cannot use the network/access resources, slower speed, higher latency), not just repeat that the device is out of range.

Do not accept a definition of range on its own (e.g. 'range is how far the signal reaches') without an effect on performance.

Do not accept 'a larger range means more devices can connect' (range is not about the number of devices/capacity).

Do not accept range confused with bandwidth/speed, e.g. 'range is the maximum amount of data that can be transferred'.