Deck 5: Physical Layer Propagation

Question 1

A length of UTP wiring is a ________.

A)run
B)fiber
C)cord
D)jacket
E)strand

Answer 1

C

Question 2

In 4-pair UTP,what is twisted?

A)All of the wires are twisted around one another.
B)The wires in each pair are twisted around each other.
C)Both A and B
D)Neither A nor B

Answer 2

B

Question 3

Which transmission medium is dominant for the wired access line between a host and the switch that serves the host?

A)4-pair UTP.
B)Optical fiber.
C)Both are used about equally.
D)Neither A nor B

Answer 3

A

Question 4

Changes in a signal during propagation are called,most generally,________.

A)distortion effects
B)attenuation effects
C)interference effects
D)propagation effects
E)transmission effects

Question 5

A ________ is a disturbance that propagates down a transmission medium to the other side,which reads it.

A)byte
B)bit
C)signal
D)frame
E)packet

Question 6

The noise floor is ________.

A)a brief increase in the noise energy
B)the maximum noise energy
C)the mean (average)noise energy
D)the minimum noise energy

Question 7

In the UTP wiring used in LANs,how many wires are there in a cord?

A)1.
B)2.
C)4.
D)8.
E)25.

Question 8

When a signal grows weaker as it travels,this is called ________.(Choose the most specific answer.)

A)a propagation effect
B)noise
C)interference
D)attenuation
E)All of the above.

Question 9

Which of the following is relatively immune to small errors?

A)Analog signaling.
B)Binary signaling.
C)Both A and B
D)Neither A nor B

Question 10

In binary signaling there is (are)________ state(s).

A)one
B)two
C)a few
D)an infinite number of

Question 11

The outer covering of a UTP cord is its ________.

A)insulation
B)coating
C)sheath
D)length
E)jacket

Question 12

Which of the following layers deals with messages?

A)The physical layer.
B)The internet layer.
C)Both A and B
D)Neither A nor B

Question 13

In UTP cables,each wire is surrounded by ________.

A)copper
B)a jacket
C)insulation
D)All of the above.

Question 14

Analog signaling is relatively immune to small errors.

Question 15

Propagation effects can make a signal unreadable at the destination.

Question 16

The physical layer ________.

A)deals with propagation effects
B)deals with messages
C)Both A and B
D)Neither A nor B

Question 17

In the UTP wiring used in LANs,how many wire pairs are there in a cord?

A)1.
B)2.
C)4.
D)8.
E)25.

Question 18

When a signal travels,this is called ________.

A)transit
B)end-to-end transmission
C)propagation
D)a propagation effect
E)transport

Question 19

Binary signaling is relatively immune to small errors.

Question 20

In digital signaling there is (are)________ state(s).

A)one
B)two
C)a few
D)an infinite number of

Question 21

UTP categories rate the ________ of cabling.

A)quality
B)cost
C)quality-of-service performance
D)error performance

Question 22

A high signal-to-noise ratio reduces ________ errors.

A)signal
B)noise
C)interference
D)attenuation
E)All of the above.

Question 23

Untwisting wire pairs no more than 1.25 cm (a half inch)at their ends reduces ________.

A)interference
B)crosstalk interference
C)terminal crosstalk interference
D)None of the above.

Question 24

When a fluorescent light interferes with UTP transmission,this is ________.

A)interference
B)crosstalk interference
C)terminal crosstalk interference
D)All of the above.

Question 25

Serial transmission is transmission over a single wire pair.

Question 26

The Ethernet standard limits UTP propagation distances to 100 meters at all speeds up to 1 Gbps.

Question 27

Cat 5e and Cat 6 wiring can carry Ethernet traffic 100 meters up to ________.

A)1 Mbps
B)10 Mbps
C)100 Mbps
D)1 Gbps
E)10 Gbps

Question 28

Parallel transmission is transmission over ________.

A)four wire pairs
B)two or more wire pairs

Question 29

Untwisting wire pairs no more than 1.25 cm (a half inch)at their ends completely eliminates terminal crosstalk interference.

Question 30

The main benefit of parallel transmission over serial transmission is ________.

A)reliability
B)speed
C)Both A and B
D)Neither A nor B

Question 31

When one pair in a UTP cord interferes with signals in other pairs,this is ________.

A)interference
B)crosstalk interference
C)terminal crosstalk interference
D)internal noise

Question 32

A noise spike is ________.

A)a brief large increase or decrease in the noise energy
B)the maximum noise energy
C)the mean (average)noise energy
D)the minimum noise energy

Question 33

In Ethernet,limiting UTP cord runs to 100 meters normally limits ________ to an acceptable level.

A)attenuation
B)noise errors
C)Both A and B
D)Neither A nor B

Question 34

Noise errors become severe before the signal attenuates to the level of the noise floor.

Question 35

As a signal propagates down a UTP cord,greater propagation distance will result in more noise errors,even if the noise level is constant.

Question 36

Which type of transmission is more widely used today?

A)Serial.
B)Parallel.
C)Both are used about equally.

Question 37

Which of the following UTP wiring quality standards governs many UTP cables for sale today?

A)Category 3.
B)Category 4.
C)Category 6.
D)Category 7.
E)All of the above.

Question 38

Twisting wires reduces ________.

A)interference
B)crosstalk interference
C)Both A and B
D)Neither A nor B

Question 39

In most versions of Ethernet,what is the maximum cord length allowed by the standard?

A)1.25 cm (a half inch).
B)100 meters.
C)There is no maximum cord length in the standard.

Question 40

What type of interference is the most frequently encountered?

A)Electromagnetic interference.
B)Crosstalk interference.
C)Terminal crosstalk interference.
D)Noise interference.

Question 41

The ability to transmit in two directions simultaneously is called parallel transmission.

Question 42

In LANs,UTP typically is used for trunk lines.

Question 43

The ability to transmit in two directions simultaneously is ________.

A)parallel communication
B)full-duplex communication
C)Both A and B
D)Neither A nor B

Question 44

Today,the main benefit of optical fiber compared with UTP is ________.

A)rugged construction
B)lower cost
C)the ability to transmit signals faster
D)the ability to span greater distances

Question 45

Which form of UTP can carry 10 Gbps signals 100 meters?

A)Cat 6.
B)Cat 6A.
C)Both A and B
D)Neither A nor B

Question 46

Which light wavelength propagates farthest in optical fiber?

A)50 nm.
B)850 nm.
C)1550 nm.
D)Both A and B

Question 47

What type of line connects switches to other switches?

A)Trunk lines.
B)Access lines.
C)Both A and B
D)Neither A nor B

Question 48

A typical optical fiber core size is ________.

A)62.5 microns
B)125 microns
C)900 microns
D)62.5 nm

Question 49

In optical fiber,we measure light in terms of ________.

A)frequency
B)wavelength
C)Either A or B

Question 50

Which light wavelength is the least expensive in optical fiber?

A)50 nm.
B)850 nm.
C)1550 nm.
D)Both A and B

Question 51

For full-duplex transmission,optical fiber normally uses ________.

A)1 strand
B)2 strands
C)4 strands
D)8 strands
E)16 strands

Question 52

Which of the following has a single connector type?

A)Optical fiber.
B)UTP.
C)Both A and B
D)Neither A nor B

Question 53

In optical fiber,a typical wavelength is ________.

A)50 microns
B)850 microns
C)Both A and B
D)Neither A nor B

Question 54

Optical fiber uses ________ signaling.(Give the most specific answer.)

A)multiple-voltage-level
B)two-voltage-level
C)on/off
D)All of the above.

Question 55

In optical fiber,light travels through the ________.

A)core
B)cladding
C)Neither A nor B

Question 56

In LANs,optical fiber typically is used in ________.

A)trunk lines
B)access lines
C)Both A and B
D)Neither A nor B

Question 57

Which light wavelength dominates use in LAN fiber?

A)62.5 nm.
B)850 nm.
C)1310 nm.
D)1550 nm.
E)None of the above.

Question 58

Compared with UTP,optical fiber is ________ expensive to buy and install today.

A)less (when all costs of purchasing and installation are considered)
B)about as
C)more

Question 59

A popular type of optical fiber connector is ________.

A)SC
B)RJ-45
C)Both A and B
D)Neither A nor B

Question 60

Lower-wavelength light dominates in optical fiber because it ________.

A)is the least inexpensive
B)can travel the farthest distances
C)Both A and B
D)Neither A nor B

Question 61

Modal dispersion limits transmission distance in ________.

A)multimode fiber
B)single-mode fiber
C)Both A and B
D)Neither A nor B

Question 62

What transmission medium do ALL DSL services use?

A)One-pair voice-grade UTP.
B)Two-pair voice-grade UTP.
C)One-pair data-grade UTP.
D)Two-pair data-grade UTP.
E)Different DSL services use different transmission media.

Question 63

Single mode fiber distance is limited primarily by ________.

A)modal dispersion
B)absorptive attenuation
C)Both A and B about equally.

Question 64

Low-speed leased lines use ________ transmission lines.

A)one-pair voice-grade UTP
B)two-pair voice-grade UTP
C)one-pair data-grade UTP
D)two-pair data-grade UTP
E)four-pair UTP

Question 65

Businesses can select multimode fiber to transmit 1000BASE-SX signals farther by ________.

A)buying fiber with lower modal bandwidth
B)buying fiber with wider core diameter
C)Both A and B
D)Neither A nor B

Question 66

Compared with single-mode fiber,multimode fiber has ________ core.

A)a wider
B)a narrower
C)the same width

Question 67

Providing service is called ________.

A)provisioning
B)signaling
C)access lining
D)loading
E)All of the above.

Question 68

What is a typical core diameter for multimode fiber?

A)62.5 microns.
B)8.3 microns.
C)Both A and B

Question 69

Why is multimode fiber used instead of single-mode fiber for LAN transmission?

A)Lower cost.
B)Higher speed.
C)Longer propagation distance.
D)All of the above.

Question 70

Single mode fiber has a core diameter of ________.

A)8.3 microns
B)62.5 microns
C)Either A or B

Question 71

Modal bandwidth is a measure of ________.

A)modal dispersion
B)multimode fiber quality
C)fiber quality
D)propagation speed

Question 72

________ is a major propagation problem in optical fiber.

A)Noise
B)Interference
C)Both A and B
D)Neither A nor B

Question 73

The residential local loop consists of ________ transmission lines.

A)one-pair voice-grade UTP
B)two-pair voice-grade UTP
C)one-pair data-grade UTP
D)two-pair data-grade UTP
E)four-pair UTP

Question 74

Multimode optical fiber quality is measured as MHz.km.

Question 75

Small form factor connectors are used in ________.

A)UTP
B)optical fiber
C)Both A and B
D)Neither A nor B

Question 76

The lowest-speed leased lines (under about 2 Mbps)use ________.

A)one-pair voice-grade UTP
B)two-pair voice-grade UTP
C)one-pair data-grade UTP
D)two-pair data-grade UTP
E)4-pair UTP

Question 77

When the light energies of multiple pulses overlap,this is ________.

A)multimode transmission
B)modal bandwidth
C)modal dispersion
D)called having modes

Question 78

Which of the following already runs to nearly all customer premises?

A)4-pair UTP.
B)1-pair VG UTP.
C)1-pair DG UTP.
D)None of the above.

Question 79

LANs normally use ________.

A)multimode fiber
B)single-mode fiber

Question 80

Multimode fiber distance is limited primarily by ________.

A)modal dispersion
B)absorptive attenuation
C)Both A and B about equally.