A school connects its computers to the network using copper Ethernet cables.
A computer in a new classroom is 150 metres from the network switch. It is connected using a copper Ethernet cable, but the connection is unreliable.
Explain why the connection is unreliable.
Mark scheme
Award up to two marks for a linked explanation such as:
- A copper Ethernet cable has a standard maximum segment length of 100 metres (1) so over 150 metres the signal is too weak to be read correctly (1)
- 150 metres is beyond the maximum range of a copper Ethernet cable (1) so the computer does not receive the data with enough signal strength (1)
- The signal weakens/degrades as it travels along the cable (1) so at 150 metres the data is corrupted/lost (1)
For both marks, the expansion must follow/associate with the statement.
Do not accept 'the cable is too long' on its own without saying that the signal weakens/does not reach the computer with enough strength.
Do not accept 'the signal is lost/weak' on its own without linking it to the distance being beyond the maximum range of copper cable.
Do not accept answers that only blame interference from walls or other devices, as the problem here is the distance.
Example answers and how they were marked
A copper Ethernet cable has a standard maximum segment length of 100 metres. The classroom is 150 metres away, so the signal has become too weak to be read correctly, which makes the connection unreliable.
Why: States the cable is beyond its maximum range (1) and links this to the signal being too weak to be read (1).
Copper Ethernet cables can only carry data for 100 metres, which is less than 150 metres.
Why: Identifies that the cable run is beyond the maximum range (1) but does not say what happens to the signal as a result.
There is interference from the walls of the classroom, which slows the signal down.
Why: Blames interference rather than distance, so there is no creditworthy point about range; the mark scheme does not accept interference as the explanation here.