Chapter 3 Questions-Physical Layer Propagation Chapter 3 Questions-Physical Layer Propagation

1. What is unique about the Physical Layer?

a.It is the only layer where encapsulation does NOT occur.

b.It and the IP layer are the only layers that are governed by standards.

c.It relies on electrical voltages to assemble data packets.

1. It is not present in wireless communications, which is nonphysical.

Reference: p. 68

2. Attenuation is an example of a propagation effect.

a.True

1. False

Reference: p. 69

3. Retransmission is an example of a propagation effect.

a.True

1. False

Reference: p. 69

4. Which of the following statements is NOT true?

a.Analog data can be converted to digital data.

b.Digital data can be converted to analog data.

c.Digital data is very susceptible to attenuation and distortion problems.

d.Both analog and digital data can be represented by voltages.

Reference: p. 69

5. Which of the following statements is true regarding the relationship between bit rate and baud rate?

a.The baud rate will always exceed the bit rate.

b.The bit rate will always exceed the baud rate.

c.The bit rate will always be less than the baud rate.

d.The bit rate and the baud rate are the same concept expressed in different words.

1. The bit rate and the baud rate measure different things.

Reference: p. 71

6. To translate voice data into a format for transmission over a digital line, you need a:

a.decoder.

b.codec.

c.modem.

d.modulator.

1. codec/modem.

Reference: p. 72

7. To translate analog voice data that was encoded for digital transmission back to analog voice, you need a:

a.codec.

b.modem.

c.modulator.

d.codec/modem.

Reference: p. 72

8. UTP cable usually contains:

a.2 wires.

b.4 wires.

c.6 wires.

d.8 wires.

Reference: p. 73

9. A(n) ______is most often found connecting PCs to the nearest hub or switch.

b.coaxial cable

c.UTP

d.modem

1. optical fiber cable

Reference: p. 73

10. Which set of advantages does the textbook associate with UTP media?

a.Designed for high speed and low attenuation.

b.Designed to support analog communications, inexpensive, easy to build or buy.

c.It is inexpensive, easy to connectorize, rugged.

d.Designed for high-interference environments.

Reference: p. 75

11. The process of signals growing weaker as they propagate is known as:

a.attenuation.

b.signal expiration.

c.connectorization.

d.default loss.

1. the signal-to-noise ratio.

Reference: p. 76

12. Which of these terms refers to the random energy within the medium that affects the quality of electrical signals on UTP?

a.Attenuation

b.Default loss

c.Noise

d.Signal Expiration

Reference: p. 75

13. As long as an electrical signal remains far above the signal-to-noise ratio threshold, noise will not be a serious problem.

a.True

1. False

Reference: p.76

14. Noise is introduced primarily by connectors in UTP media.

a.True

1. False

Reference: p. 76

15. What is the standard for transmission media (both UTP and optical fiber)?

a.TIA/EIA-232

b.TIA/EIA-568

c.Ethernet

d.Plenum

Reference: p. 73

16. When even moderate electromagnetic interference is present, UTP wiring cannot be used.

a.True

1. False

Reference: p. 77

17. EMI between pairs in a single UTP cord creates a condition known as:

a.attenuation.

b.default loss.

c.crosstalk.

d.noise.

1. signal expiration.

Reference: p. 78

18. Limiting the distance of UTP cords to 100 meters is done to control the number of ______.

a.noise errors

b.EMI errors

c.terminal crosstalk interference errors

d.All of the above.

Reference: p. 77

19. Terminal crosstalk interference is controlled by _____.

a.limiting the length of the cord

b.twisting the wires

c.Both of the above.

d.Neither a. nor b.

Reference: p. 78

20. UTP wires are normally twisted together to reduce the occurrence of:

a.EMI.

b.noise.

c.accidental stretching of the wires.

d.attenuation.

Reference: p. 77

21. A signal propagates down a wire. If the noise level is constant, how does the noise error rate change as distance increases?

a.The number of noise errors increases.

b.The number of noise errors stays the same.

c.The number of noise errors decreases.

d.There will be no noise errors.

Reference: p. 76

22. Serial transmission is usually faster than parallel data transmission.

a.True

1. False

Reference: p. 80

23. Optical fiber:

a.sends signals as voltage changes.

b.has high attenuation.

c.is not susceptible to EMI.

d.is most commonly used to connect the desktop to the nearest hub or switch.

1. is becoming less popular because of its fragile nature.

Reference: p. 80

24. In optical fiber, light travels through the _____.

a.core

c.Both of the above.

d.Neither a. nor b.

Reference: p. 80

25. In optical fiber, you use _____ to describe the signal.

a.wavelength

1. frequency (Hz)

Reference: p. 81

26. Optical fiber:

a.contains in-fiber converters to translate electrical signals into beams of light.

b.can easily transmit analog data using changes in the intensity of the light beam.

c.contains two pieces of glass, a core and a cladding cylinder surrounding the core.

d.is most commonly used to connect the desktop to the nearest hub or switch.

1. is becoming less popular because of its fragile nature.

Reference: p. 82

27. Either lasers or light emitting diodes can be used to generate optical fiber signal.

a.True

1. False

Reference: p. 80

28. Full-duplex communication:

a.allows more than one user to communicate with a server at the same time.

b.allows a station to send and receive at the same time.

c.ensures that problems with EMI and noise do not slow the speed of communications.

d.allows for the use of different types of media in a network.

1. allows for voice and data traffic to use the same media concurrently.

Reference: p. 82

29. Multimode fiber has a thicker core than single-mode fiber.

a.True

1. False

Reference: p. 83

30. Multimode fiber is more expensive than single-mode fiber.

a.True

1. False

Reference: p. 83

31. Multimode fiber allows signals to travel for longer distances than single-mode fiber does.

a.True

1. False

Reference: p. 84

32. Which statement is NOT true about fiber optical fiber?

a.The main propagation problem for optical fiber is temporal dispersion.

b.Multimode fiber is advantageous compared to single-mode fiber because it provides for full-duplex communications.

c.Noise is not a problem in optical fiber.

d.Multiple signals can be transmitted on fiber by multiplexing the signals.

1. As light signals bounce and bend inside the fiber, the quality of the transmissiondecreases.

Reference: p. 82

33. Mode problems in optical fiber can be controlled by _____.

a.limiting the lengths of multimode fiber cords

b.using single-mode fiber

c.Both of the above.

d.Neither a. nor b.

Reference: p. 83

34. You need radio communication with trucks within a state, using a network of radio towers. You would use _____ antennas on the trucks.

a.omnidirectional

b.dish

1. Either of the above.

Reference: p. 84

35. What things can be changed to vary the information contained in a signal?

a.Signal to noise ratio, Amplitude, Frequency

b.Frequency, Wavelength, Signal-to-noise ratio

c.Wavelength, Frequency, Amplitude

d.Currency, Amplitude, Wavelength

e.Phonic, Amplitude, Frequency

Reference: p. 86

36. If the lowest frequency used by a channel is 40.5 MHz and the highest frequency used by that same channel is 45 MHz, the bandwidth of the channel is:

a.0.5 MHz

b.4.5 MHz

c.40.5 MHz

d.85.5 MHz

e.Undetermined; not enough information to decide.

Reference: p. 87

37. Which of the following reflects the correct ordering of terms from smallest to largest?

a.Frequency spectrum, channel, service band

b.Channel, service band, frequency spectrum

c.Service band, frequency spectrum, channel

d.Channel, frequency spectrum, service band

e.Service band, channel, frequency spectrum

Reference: p. 87

38. What happens to the maximum possible transmission speed in a channel as the channel’s bandwidth is increased?

a.The maximum possible transmission speed decreases.

b.The maximum possible transmission speed increases.

c.The maximum possible transmission speed is not affected.

Reference: p. 87

39. Signals attenuate most quickly when using:

a.single-mode fiber optic transmission.

b.multimode fiber optic transmission.

c.wireless transmission.

d.UTP.

e.Cable transmission.

Reference: p. 89

40. Which is NOT one of the major topologies?

a.Ethernet

b.Mesh

c.Point-to-point

d.Ring

e.Star

Reference: pp. 90-91

41. Which topology allows multiple routes for a signal to get to a point on the network?

a.Ethernet

b.Mesh

c.Point-to-Point

d.Ring

e.Star

Reference: p. 90

42. Which topology is often referred to as a hierarchical network topology?

a.Ethernet

b.Mesh

c.Bus

d.Ring

e.Extended Star

Reference: p. 90

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