Modules 4 – 7

What is the purpose of the OSI physical layer ?

• controlling access to media

• transmitting bits across the local media

• performing error detection on received frames

• exchanging frames between nodes over physical network media

Why are two strands of fiber used for a single fiber optic connection ?

• The two strands allow the data to travel for longer distances without degrading.

• They prevent crosstalk from causing interference on the connection.

• They increase the speed at which the data can travel.

• They allow for full-duplex connectivity.

Which characteristic describes crosstalk ?

• the distortion of the network signal from fluorescent lighting

• the distortion of the transmitted messages from signals carried in adjacent wires

• • the weakening of the network signal over long cable lengths

• the loss of wireless signal over excessive distance from the access point

Which procedure is used to reduce the effect of crosstalk in copper cables ?

• requiring proper grounding connections

• twisting opposing circuit wire pairs together

• wrapping the bundle of wires with metallic shielding

• designing a cable infrastructure to avoid crosstalk interference

• avoiding sharp bends during installation

A network administrator is measuring the transfer of bits across the company backbone for a mission critical financial application. The administrator notices that the network throughput appears lower than the bandwidth expected. Which three factors could influence the differences in throughput ? (Choose three)

• the amount of traffic that is currently crossing the network

• the sophistication of the encapsulation method applied to the data

• the type of traffic that is crossing the network

• the latency that is created by the number of network devices that the data is crossing

• the bandwidth of the WAN connection to the Internet

What are two characteristics of fiber-optic cable ? (Choose two)

• It is not affected by EMI or RFI.

• Each pair of cables is wrapped in metallic foil.

• It combines the technique of cancellation, shielding, and twisting to protect data.

• It typically contains 4 pairs of fiber-optic wires.

• It is more expensive than UTP cabling is.

What is a primary role of the Physical layer in transmitting data on the network ?

• create the signals that represent the bits in each frame on to the media

• provide physical addressing to the devices

• determine the path packets take through the network

• control data access to the media

With the use of unshielded twisted-pair copper wire in a network, what causes crosstalk within the cable pairs ?

• the magnetic field around the adjacent pairs of wire

• the use of braided wire to shield the adjacent wire pairs

• the reflection of the electrical wave back from the far end of the cable

• the collision caused by two nodes trying to use the media simultaneously

Refer to the graphic. What type of cabling is shown ?

• STP

• UTP

• Coax

• Fiber

In addition to the cable length, what two factors could interfere with the communication carried over UTP cables ? (Choose two)

• crosstalk

• bandwidth

• size of the network

• signal modulation technique

• electromagnetic interference