The differences between no signal and signal can be less than 1 volt. In fact, noise voltages can even be interpreted as signals. This is one reason why the cabling media must be protected from noise sources and be free from induced noise voltages. Because a LAN comprises many components, its often difficult to decide where to start finding the problem. However, there are a few basic rules we can learn which will point us in the right direction, with the aim of minimizing downtime.
Information is vital for troubleshooting.
Needless to say, cabling at installation time should be certified in writing, along with test results detailing the measurements taken. There are restrictions on cable types, distances and number of workstations attached. This describes the manner in which the various hardware equipment of the LAN is interconnected. These are problems like inability to run certain applications can't access certain files or directories Often problems are sporadic and intermittent in nature. With intermittent faults, it is important to obtain information about which users noticed it first what were they doing when it failed has this happened before is it repeatable is there any difference between this and the last time The trouble-shooter must know the hardware and software configurations of the various workstations and servers on the network.