Physical Network Media- Point to Remember (CISA-Domain 4)

Point to remember for CISA Exam:

(1)In any given situation, fiber-optic cables have proven to be more secure than the other media. They have very low transmission loss, not affected by EMI and preferred choice for high volumes and long distance calls.

(2)When CISA question is about transmission error that can occur in wired as well as wireless communication, our answer should be attenuation.

(3)It is essential to understand the difference between diverse routing and alternate routing. The method of routing traffic through split-cable facilities or duplicate-cable facilities is called diverse routing. Whereas the method of routing information via an alternative medium, such as copper cable or fiber optics is called alternate routing.

(4)Also, CISA aspirant should be able to differentiate between last mile and long haul. Last mile provide redundancy for local loop whereas long haul provide redundancy for long distance availability.

(5)It is also very critical to understand the meaning of terms such as attenuation, EMI and cross talks:


-Attenuation is the weakening of signals during transmission.

-Attenuation exists in both wired and wireless transmissions.

-Length of wire impacts the severity of attenuation.

(ii)Electromagnetic Interference (EMI):

-EMI is a disturbance generated by an external source that affects an electrical circuit.

-The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data.

-EMI is caused by electrical storms or noisy electrical equipments (e.g. motors, fluorescent lighting, radio transmitters etc.)


Crosstalk is electromagnetic interference from one unshielded twisted pair to another twisted pair, normally running in parallel.