By Glen E. Clarke, Edward Tetz, Timothy Warner

You will be tested on several different networking devices for the A+ Exams, including the repeater/extender. One way to increase the distance of a cable length is to use a repeater, which regenerates a signal so it can travel the extra distance.

One major concern with cabling is the maximum usable length of the cable. For example, UTP cabling has a maximum length of 100 meters, and Thinnet has a maximum length of 185 meters.

The reason for putting a maximum distance on cable lengths is that the signal traveling along the cable becomes too weak to read at the destination system by the time the maximum length is reached. The term for reduced strength in the signal is attenuation. The receiving computer cannot read the information, and thus does not acknowledge that it received the data. When the sending computer does not receive an acknowledgment, it simply resends the data. This causes the information to be resubmitted, generating more network traffic.

For example, the repeater shown joins two lengths of Thinnet coaxial cable. It joins the two cable lengths so that the signal can travel the distance from computer A to computer B. Note that this distance exceeds 185 meters, which is the maximum distance of Thinnet. When the signal hits the repeater, the repeater rebuilds the signal so that it can travel another 185 meters.

comptia-certification-repeater
A repeater is used to regenerate the signal.

An extender is a device that you can use to connect two cable lengths together to create a much longer cable length. The problem with an extender is that it does not reamplifiy the signal, so be careful not to exceed the cable length for the type of cable you are extending. For example, twisted pair cabling has a maximum length of 100 meters, so you need to ensure each cable length you are joining together with an extender does not exceed 100 meters.