46. Name the advantage of optical fiber over twisted pair and coaxial cable.
47. What is the disadvantage of optical fiber as a transmission medium?
Installation / Maintenance.
Unidirectional.
Cost – More expensive than those of other guided media.
48. What does the term modem stands for ?
Modem stands for modulator / demodulator.
49. What is the function of a modulator?
A modulator converts a digital signal into an analog signal using ASK, FSK, PSK or QAM.
50. What is the function of a demodulator?
A demodulator converts an analog signal into a digital signal.
51. What is an Intelligent modems?
Intelligent modems contain software to support a number of additional functions such as automatic answering and dialing.
52. What are the factor that affect the data rate of a link?
The data rate of a link depends on the type of encoding used and the bandwidth of the medium.
53. Define Line coding.
Line coding is the process of converting binary data, a sequence of bits, to a digital signal.
54. For n devices in a network, what is the number of cable links necessary for mesh, ring, bus and star networks.
Number of links for mesh topology : n (n – 1) / 2.
Number of links for ring topology : n – 1.
Number of links for bus topology : one backbone and n drop lines.
Number of links for star topology : n.
55. Write the design issues of datalink layer?
1) Services provided to network layer.
2) Framing
3) Error control
4) Flow control
- Higher bandwidth.
- Less signal attenuation.
- Immunity to electromagnetic interference.
- Resistance to corrosive materials.
- More immune to tapping.
- Light weight.
47. What is the disadvantage of optical fiber as a transmission medium?
Installation / Maintenance.
Unidirectional.
Cost – More expensive than those of other guided media.
48. What does the term modem stands for ?
Modem stands for modulator / demodulator.
49. What is the function of a modulator?
A modulator converts a digital signal into an analog signal using ASK, FSK, PSK or QAM.
50. What is the function of a demodulator?
A demodulator converts an analog signal into a digital signal.
51. What is an Intelligent modems?
Intelligent modems contain software to support a number of additional functions such as automatic answering and dialing.
52. What are the factor that affect the data rate of a link?
The data rate of a link depends on the type of encoding used and the bandwidth of the medium.
53. Define Line coding.
Line coding is the process of converting binary data, a sequence of bits, to a digital signal.
54. For n devices in a network, what is the number of cable links necessary for mesh, ring, bus and star networks.
Number of links for mesh topology : n (n – 1) / 2.
Number of links for ring topology : n – 1.
Number of links for bus topology : one backbone and n drop lines.
Number of links for star topology : n.
55. Write the design issues of datalink layer?
1) Services provided to network layer.
2) Framing
3) Error control
4) Flow control
