Excerpt for CISA Exam - Testing Concept-Network Physical Media (Fiber Optic/ UTP/STP/Co-axial) (Domain-4) by , available in its entirety at Smashwords


Testing Concept-Network Physical Media (Fiber Optic/ UTP/STP/Co-axial)

Hemang Doshi


Details about this E-Book:

The objective of this e-book is to ensure that CISA candidate get adequate knowledge on concept of various network physical media such as fiber optic, twisted pair, co-axial etc. Concepts have been simplified for easy reference of CISA candidates.

Questions, Answers and Explanation (QAE) on concept are designed in accordance with CISA exam pattern.

Types of Network Physical Media

CRM covers following types of network physical media specifications:

  • Twisted Pairs ( shielded twisted pairs and unshielded twisted pairs)

  • Fiber-optics

  • Infrared & radio (wireless)

(1)Twisted Pair:

-Twisted pairs are also known as copper circuits.

-Twisted pair can be either shielded twisted pair or unshielded twisted pair.

Shielded Twisted Pair (STP):

-Two insulated wires are twisted around each other, with current flowing through them in opposite direction.

-This reduces the opportunity for cross talk and allows for lower sensitivity for electromagnetic disturbances.

Unshielded Twisted Pair (UTP):

-For unshielded twisted pair a disadvantage is that it is not immune to effect of electromagnetic interface (EMI).

-Unshielded twisted pair should be away from potential interference such as fluorescent lights.

-Parallel runs of cable over long distances should be avoided since the signals on one cable can interfere with signals on adjacent cables (i.e. cross talk).


-Glass fibers are used to carry binary signals as flashes of light.

-Fiber-optic systems have very low transmission loss.

-Fiber-optics are not affected by electromagnetic interference (EMI).

- Fiber-optic cables have proven to be more secure than the other media.

-Fiber is preferred choice for high volume and long distance calls.

(3)Coaxial Cables

What is alternate routing and diverse routing?

Alternate Routing:

Alternative routing is the method of routing information via an alternative medium, such as copper cable or fiber optics.

Alternate routing can be further bifurcated in two types:

Last mile circuit protection:

Last mile circuit protection provides redundancy for local communication loop.

Long haul network diversity:

Long haul network diversity provides redundancy for long distance availability.

Diverse Routing:

Diverse routing is the method of routing traffic through split-cable facilities or duplicate-cable facilities.

Difference between alternate routing and diverse routing:

Other Important Terms:


-Attenuation is the weakening of signals during transmission.

-Attenuation exists in both wired and wireless transmissions.

-Length of wire impacts the severity of attenuation.

(2)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.

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.

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