Each type of network cable has a maximum useable length. If you go beyond that length, the signal will be too weak to be useful.

Of course, computers on a real network can easily be more than 200 metres apart. Therefore the network cable is split up into segments. Each segment is less than the maximum length allowed. Joining the segments together is a device known as a 'Repeater'.

 A Repeater boosts the signal back to its correct level.

Here are some typical maximum cable lengths: