When a cable technician (For network) is done installing all the CAT5, why

[Eddie]

is neccesary to make a test? What would be the tools that a technician needs in order to perform this test?

 

[SlapStickBilly]

They have a special tool that checks continuity across all the wires to make sure they did not miswire anything. There are like 8 wires (I think) that have to be manually pressed into a cat5 jack, and it is very easy for even a professional installer to get one wrong.