forouzan qanda

8/11/2019 Forouzan QandA

1/40

1.

There are ______________ Internet service providers.

A) regional

B) local

C) national and international

D) all of the above

2. ______ refers to the physical or logical arrangement of a network.

A)

TopologyB) Mode of operation

C)

Data flow

D)

None of the above

3. A ______ is a data communication system spanning states, countries, or the whole world.

A) MAN

B) WAN

C)

LAN

D) none of the above

4. A _______ connection provides a dedicated link between two devices.

A)

primary

B) multipoint

C) point-to-point

D)

secondary

5. Which topology requires a multipoint connection?

A) Bus

B) Star

C) Mesh

D)

Ring

6.

A ________ is a set of rules that governs data communication.

A) protocol

B) forum

C)

standard


7. In a ______ connection, two and only two devices are connected by a dedicated link.

A)

multipointB) point-to-point

C)

(a) and (b)


8. The information to be communicated in a data communications system is the _______.

A) Medium

B)

Protocol

C) Message

D) Transmission

9. ________ defines how a particular pattern to be interpreted, and what action is to be taken based on that

interpretation.

A) Syntax

B) Semantics

C)

Timing

D)

None of the above

10. Frequency of failure and network recovery time after a failure are measures of the _______of a network.

A) Performance

B) Security

C) Reliability

D) Feasibility

11. A television broadcast is an example of _______ transmission.

A) half-duplex


2/40


3/40

C)

(a) and (b)


22. Which organization has authority over interstate and international commerce in the communications

field?

A) FCC

B) IEEE

C)

ITU-TD) ISOC

23.

In the original ARPANET, _______ were directly connected together.

A)

routers

B) host computers

C) networks

D) IMPs

24.

Communication between a computer and a keyboard involves ______________ transmission.

A) simplex

B) half-duplex

C)

full-duplex

D) ; automatic

25. Which topology requires a central controller or hub?

A)

Mesh

B) Bus

C) Star

D) Ring

26. The _______ is the physical path over which a message travels.

A)

Protocol

B)

Signal

C) Medium

D) All the above

27.

In a _______ connection, more than two devices can share a single link.

A) multipoint

B) point-to-point

C)

primaryD)

secondary

28.

_______ refers to the structure or format of the data, meaning the order in which they are presented.

A) Semantics

B) Syntax

C) Timing

D)

All of the above

29. An unauthorized user is a network _______ issue.

A) Security

B) Reliability

C)

Performance

D) All the above

30.________ is an idea or concept that is a precursor to an Internet standard.

A)

RCF

B)

ID

C) RFC


31. In _______ transmission, the channel capacity is shared by both communicating devices at all times.

A)

simplex

B) half-duplex

C) full-duplex

D) half-simplex


4/40

32. The ______ layer adds a header to the packet coming from the upper layer that includes the logical

addresses of the sender and receiver.

A)

data link

B) network

C) physical

D)

none of the above33.

Which of the following is an application layer service?

A) File transfer and access

B) Mail service

C) Remote log-in

D) All the above

34.

When data are transmitted from device A to device B, the header from A's layer 4 is read by B's _______

layer.

A) Transport

B)

Application

C) Physical

D) None of the above

35.__________ provides full transport layer services to applications.

A)

UDP

B) TCP

C) ARP


36. The process-to-process delivery of the entire message is the responsibility of the _______ layer.

A) Transport

B) Application

C) Physical

D) Network

37.

The ______ layer is responsible for moving frames from one hop (node) to the next.

A) transport

B) data link

C)

physicalD)

none of the above

38. The _______ layer is responsible for delivering data units from one station to the next without errors.

A) physical

B) data link

C)

transport

D) network

39. The session, presentation, and application layers are the ____ support layers.

A) user

B)

network

C) both (a) and (b)

D) neither (a) nor (b)

40.

The physical, data link, and network layers are the ______ support layers.

A)

network

B) user

C) both (a) and (b)


41.

The ________ layer is responsible for the process-to-process delivery of the entire message.

A) transport

B) physical

C) network


5/40

D)

data link

42. The _______ layer lies between the network layer and the application layer.

A) Data link

B) Transport

C)

Physical


43.

The Internetworking Protocol (IP) is a ________ protocol.A) connection-oriented

B)

reliable

C)

both a and b


44. The _______ layer links the network support layers and the user support layers.

A) session

B) transport

C) data link

D) network

45.

ICMPv6 includes _______.

A) IGMP

B) ARP

C)

RARP

D) a and b

46. The ____ address uniquely defines a host on the Internet.

A) IP

B) port

C)

specific

D)

physical

47. The _______ layer coordinates the functions required to transmit a bit stream over a physical medium.

A) data link

B)

transport

C) network

D) physical

48.

The ______ layer is responsible for the source-to-destination delivery of a packet across multiple networklinks.

A) network

B) physical

C) data link

D) transport

49.

Mail services are available to network users through the _______ layer.

A) Transport

B) Physical

C) Data link

D) Application

50. The ____ created a model called the Open Systems Interconnection, which allows diverse systems to

communicate.

A)

IEEE

B) ISO

C) OSI


51. The _______ layer changes bits into electromagnetic signals.

A) Physical

B) Transport

C) Data link



6/40

52.

IPv6 has _______ -bit addresses.

A) 128

B) 32

C) 64

D)

variable

53. The_____ address identifies a process on a host.

A)

specificB) port

C)

IP

D)

physical

54. The_________ layer is responsible for the delivery of a message from one process to another.

A) transport

B) network

C)

physical


55. The _________ layer enables the users to access the network.

A) application

B) physical

C) data link

D)

transport

56. The TCP/IP _______ layer is equivalent to the combined session, presentation, and application layers of

the OSI model.

A) data link

B) network

C)

physical

D) application

57. When a host on network A sends a message to a host on network B, which address does the router look

at?

A) logical

B) physical

C) port

D)

none of the above58.

As the data packet moves from the upper to the lower layers, headers are _______.

A)

Rearranged

B) Removed

C) Added

D) Modified

59.

The physical layer is concerned with the movement of _______ over the physical medium.

A) dialogs

B) protocols

C) bits

D)

programs

60. To deliver a message to the correct application program running on a host, the _______ address must be

consulted.

A)

physical

B) port

C) IP


61. Ethernet uses a ______ physical address that is imprinted on the network interface card (NIC).

A)

32-bit

B) 6-byte

C) 64-bit



7/40

62.

The _______ layer is the layer closest to the transmission medium.

A) Network

B) Transport

C) Physical

D)

Data link

63. The OSI model consists of _______ layers.

A)

eightB) seven

C)

five

D)

three

64. The ________ address, also known as the link address, is the address of a node as defined by its LAN or

WAN.

A) IP

B)

port

C) specific

D) physical

65.

Layer 2 lies between the physical layer and the _______ layer.

A) Data link

B) Transport

C)

Network


66. Why was the OSI model developed?

A) The rate of data transfer was increasing exponentially

B) Standards were needed to allow any two systems to communicate

C)

Manufacturers disliked the TCP/IP protocol suite.

D)

None of the above

67. In the OSI model, as a data packet moves from the lower to the upper layers, headers are _______.

A) removed

B)

added

C) rearranged

D) modified

68.

In the OSI model, when data is transmitted from device A to device B, the header from A's layer 5 is readby B's _______ layer.

A) session

B) physical

C) transport

D) presentation

69.

The seven-layer _____ model provides guidelines for the development of universally

compatible networking protocols.

A)ISO

B)OSI

C)

IEEE


70. The Internet model consists of _______ layers.

A)

Eight

B)

Seven

C)Five

D) Three

71. In the OSI model, what is the main function of the transport layer?

A) process-to-process message delivery

B)node-to-node delivery

C)synchronization

D) updating and maintenance of routing tables


8/40

72.

_______ is a process-to-process protocol that adds only port addresses, checksum error control, and

length information to the data from the upper layer.

A)IP

B)TCP

C)UDP


73.

The ______ layer establishes, maintains, and synchronizes the interactions between communicatingdevices.

A) session

B)

physical

C) transport

D) network

74. A port address in TCP/IP is ______ bits long.

A) 16

B) 32

C) 48

D)

none of the above

75. In the OSI model, encryption and decryption are functions of the ________ layer.

A) application

B)

presentation

C) session

D) transport

76. TCP/IP is a ______ hierarchical protocol suite developed ____ the OSI model.

A) five-layer; before

B)

six-layer; before

C)

seven-layer; before

D) five-layer; after

77. The ________ address, also known as the link address, is the address of a node as defined by its LAN or

WAN.

A) logical

B) port

C)

physicalD)

none of the above

78.

The _______ model shows how the network functions of a computer ought to be organized.

A) ANSI

B) CCITT

C) ISO

D) OSI

79. The _______ layer ensures interoperability between communicating devices through transformation of

data into a mutually agreed upon format.

A) network

B) presentation

C) transport

D) data link

80.

If the maximum amplitude of a sine wave is 2 V, the minimum amplitude is ________ V.

A)

2

B) 1

C) -2

D) between -2 and 2

81.

_________ can impair a signal.

A) Noise

B) Attenuation

C) Distortion


9/40

D) All of the above

82.________is the rate of change with respect to time.

A) Time

B) Frequency

C)

Amplitude

D) Voltage

83.

A signal is measured at two different points. The power is P1 at the first point and P2 at the second point.The dB is 0. This means ________.

A) P2 equals P1

B)

P2 is zero

C) P2 is much larger than P1

D) P2 is much smaller than P1

84. Baseband transmission of a digital signal is possible only if we have a ____ channel.

A)

bandpass

B) low-pass

C) high rate

D)

low rate

85.________ is a type of transmission impairment in which the signal loses strength due to the resistance of

the transmission medium.

A)

Distortion

B) Attenuation

C) Noise

D) Decibel

86. A sine wave in the ______ domain can be represented by one single spike in the _____ domain.

A)

time; phase

B)

frequency; time

C) time; frequency

D) phase; time

87.

If the bandwidth of a signal is 5 KHz and the lowest frequency is 52 KHz, what is the highest frequency?

A) 5 KHz

B) 47 KHz

C)

57 KHzD)

10 KHz

88.

In a time-domain plot, the horizontal axis is a measure of ________.

A) phase

B) signal amplitude

C) frequency

D) time

89._______ data are continuous and take continuous values.

A) digital

B) analog

C)

a or b


90. Frequency and period are ______.

A)

proportional to each other

B) inverse of each other

C) the same


91. When propagation speed is multiplied by propagation time, we get the ________.

A)

wavelength of the signal

B) throughput

C) distance a signal or bit has traveled

D) distortion factor


10/40

92.

A _________ sine wave is not useful in data communications; we need to send a _______ signal.

A) single-frequency; composite

B) composite; single-frequency This is the correct answer.

C) single-frequency; double-frequency

D)

none of the above

93. The _________ product defines the number of bits that can fill the link.

A)

delay-amplitudeB) frequency-amplitude

C)

bandwidth-period

D) bandwidth-delay

94._______ signals can have only a limited number of values.

A) Digital

B) Analog

C)

A or B


95. Before data can be transmitted, they must be transformed to ________.

A)

periodic signals

B) electromagnetic signals

C) aperiodic signals

D)

low-frequency sine waves

96. Data can be ________.

A) digital

B) analog

C) A or B

D)

none of the above

97.

________ is a type of transmission impairment in which the signal loses strength due to the different

propagation speeds of each frequency that makes up the signal.

A) Noise

B) Distortion

C) Attenuation

D) Decibel

98.

Signals can be ________.A)

digital

B)

analog

C) either (a) or (b)


99. A sine wave is ________.

A)

periodic and discrete

B) aperiodic and discrete

C) periodic and continuous

D) aperiodic and continuous

100.

_______ data have discrete states and take discrete values.

A) Analog

B) Digital

C)

A or B

D)

None of the above

101.For a ______ channel, we need to use the Shannon capacity to find the maximum bit rate.

A) noiseless

B) noisy

C)

low-pass

D) bandpass

102.What is the bandwidth of a signal that ranges from 1 MHz to 4 MHz?

A) 1 KHz


11/40

B) 3 MHz

C) 4 MHz


103._____ signals can have an infinite number of values in a range.

A) Analog

B) Digital

C)

A or BD) None of the above

104.

A(n)_________ signal is a composite analog signal with an infinite bandwidth.

A) digital

B) analog



105.

A periodic signal completes one cycle in 0.001 s. What is the frequency?

A) 1 Hz

B) 100 Hz

C) 1 KHz

D) 1 MHz

106.The _____ of a composite signal is the difference between the highest and the lowest frequencies

contained in that signal.

A) period

B) bandwidth

C) frequency

D) amplitude

107.

________ is a type of transmission impairment in which an outside source such as crosstalk corrupts a

signal.

A) Noise

B) Distortion

C)

Attenuation

D) Decibel

108._______ describes the position of the waveform relative to time 0.

A)

AmplitudeB) Phase

C)

Frequency

D) Voltage

109.Given two sine waves A and B, if the frequency of A is twice that of B, then the period of B is ________

that of A.

A)

one-half

B) twice

C) the same as

D) indeterminate from

110.

As frequency increases, the period ________.

A) increases

B) decreases

C)

doubles

D)

remains the same

111.If the available channel is a ____ channel, we cannot send a digital signal directly to the channel.

A) low-pass

B) low rate

C) bandpass

D) high rate

112.For a ______ channel, the Nyquist bit rate formula defines the theoretical maximum bit rate.

A) low-pass


12/40


13/40


14/40

133. _______ encoding has a transition at the beginning of each 0 bit.

A) Differential Manchester

B) Manchester

C) RZ

D) All the above

134. In ______, the change or lack of change in the level of the voltage determines the value of the bit.

A) NRZ-LB) NRZ-I

C) both (a) and (b)


135. In ___________ there is always a transition at the middle of the bit, but the bit values are determined at

the beginning of the bit. If the next bit is 0, there is a transition; if the next bit is 1, there is none.

A) Manchester

B) differential Manchester

C) both (a) and (b)


136. In _______ encoding, the duration of the bit is divided into two halves. The voltage remains at one level

during the first half and moves to the other level in the second half. The transition at the middle of the bit

provides synchronization.

A) Manchester

B) differential Manchester

C) both (a) and (b)


137. The ________ mode provides synchronization for the entire stream of bits must. In other words, it

guarantees that the data arrive at a fixed rate.

A) isochronous

B) synchronous

C) asynchronous


138. The idea of RZ and the idea of NRZ-I are combined into the ________ scheme.

A) Manchester

B) differential ManchesterC) both (a) and (b)


139. In decoding a digital signal, the receiver calculates a running average of the received signal power, called

the _______.

A) base

B) line

C) baseline


140. In _________ transmission, we send bits one after another without start or stop bits or gaps. It is the

responsibility of the receiver to group the bits.

A) synchronous

B) asynchronous

C) isochronous


141. ______ finds the value of the signal amplitude for each sample; ____ finds the change from the previous

sample.

A) DM; CM

B) DM; PCM

C) PCM; DM


142. ______ substitutes four consecutive zeros with 000V or B00V.


15/40

A) HDB3

B) B4B8

C) B8ZSf


143. The ______ scheme uses three levels (+V, 0, and -V) and three transition rules to move between the

levels.

A) 4B5BB) MLT-3

C) 2B1Q


144. While there is (are) only _____ way(s) to send parallel data, there is (are) _____ subclass(es) of serial

transmission.

A) one; two

B) one; three

C) two; three


145. Which quantization level results in a more faithful reproduction of the signal?

A) 2

B) 8

C) 16

D) 32

146. A _________ digital signal includes timing information in the data being transmitted.

A) self-synchronizing

B) self-transmitted

C) self-modulated


147. In _______ transmission, bits are transmitted over a single wire, one at a time.

A) asynchronous serial

B) synchronous serial

C) parallel

D) (a) and (b)

148. The first step in PCM is ________.A) quantization

B) sampling

C) modulation


149. _______ encoding has a transition at the middle of each bit.

A) Manchester

B) Differential Manchester

C) RZ

D) All the above

150. In ______ transmission, we send 1 start bit (0) at the beginning and 1 or more stop bits (1s) at the end of

each byte.

A) synchronous

B) asynchronous

C) isochronous


151. In _______ transmission, bits are transmitted simultaneously, each across its own wire.

A) Asynchronous serial

B) Synchronous serial

C) Parallel

D) (a) and (b)

152. Which encoding method uses alternating positive and negative values for 1s?


16/40

A) AMI

B) RZ

C) NRZ-I

D) Manchester

153. The data rate is sometimes called the ___ rate.

A) bit

B) baudC) signal


154. _______ provides redundancy to ensure synchronization and inherent error detection.

A) Line coding

B) Block coding

C) Scrambling


155. In _______ transmission, a start bit and a stop bit frame a character byte.

A) synchronous serial

B) asynchronous serial

C) parallel

D) (a) and (b)

156. Two common scrambling techniques are ________.

A) B8ZS and HDB3

B) AMI and NRZ

C) NRZ and RZ

D) Manchester and differential Manchester

157. ___________ conversion involves three techniques: line coding, block coding, and scrambling.

A) Analog-to-analog

B) Analog-to-digital

C) Digital-to-analog

D) Digital-to-digital

158. The _____ scheme uses data patterns of size 2 and encodes the 2-bit patterns as one signal element

belonging to a four-level signal.

A) MLT-3B) 4B5B

C) 2B1Q


159. In _____, the level of the voltage determines the value of the bit.

A) NRZ-I

B) NRZ-L

C) both (a) and (b)


160. ________ is the process of converting digital data to a digital signal.

A) Line coding

B) Block coding

C) Scrambling


161. In a _____ scheme, all the signal levels are on one side of the time axis, either above or below.

A) unipolar

B) polar

C) bipolar

D) all of the above

1. In ________, the amplitude of the carrier signal is varied to create signal elements. Both frequency and

phase remain constant


17/40

A) PSK

B) ASK

C) FSK

D) QAM

163.

How many carrier frequencies are used in BPSK?

A) 0

B) 1C) 2


164.

The constellation diagram of 16-QAM has ______ dots.

A) 4

B) 8

C) 16


165.AM and FM are examples of ________ conversion.

A) analog-to-analog

B) digital-to-digital

C) analog-to-digital

D) digital-to-analog

166.

The Federal Communications Commission (FCC) allows ______ kHz for each FM station.

A) 20

B) 100

C) 200


167.

Analog-to-analog conversion is needed if the available bandwidth is _______.

A) band-pass

B) low-pass



168.In _____ transmission, the frequency of the carrier signal is modulated to follow the changing voltage

level (amplitude) of the modulating signal. The peak amplitude and phase of the carrier signal remain

constant, but as the amplitude of the information signal changes, the frequency of the carrier changescorrespondingly.

A) AM

B) FM

C) PM


169.

How many carrier frequencies are used in QPSK?

A) 0

B) 2

C) 1


170.Which of the following is not a digital-to-analog conversion?

A) FSK

B) ASK

C) AM

D) PSK

171._______ conversion is the process of changing one of the characteristics of an analog signal based on the

information in the digital data.

A) Analog-to-analog

B) Digital-to-digital

C) Digital-to-analog

D) Analog-to-digital


18/40

172.

If the baud rate is 400 for a QPSK signal, the bit rate is ________ bps.

A) 100

B) 400

C) 800

D) 1600

173.In ________, the phase of the carrier is varied to represent two or more different signal elements. Both

peak amplitude and frequency remain constant.A) PSK

B) FSK

C) ASK

D) QAM

174.Which of the following is not an analog-to-analog conversion?

A) QAM

B) AM

C) PM

D) FM

175.

How many carrier frequencies are used in BASK?

A) 0

B) 1

C) 2


176.Quadrature amplitude modulation (QAM) is a combination of ___________.

A) PSK and FSK

B) ASK and FSK

C) ASK and PSK


177.In _________, the frequency of the carrier signal is varied to represent data. Both peak amplitude and

phase remain constant.

A) ASK

B) FSK

C) PSK

D) QAM178.

If the bit rate for an ASK signal is 1200 bps, the baud rate is ________.

A) 1200

B) 600

C) 400

D) 300

179.

The constellation diagram of BPSK has ______ dots.

A) 0

B) 1

C) 2


180.The constellation diagram of QPSK has ______ dots.

A) 4

B) 2

C) 1


181.In _______, the peak amplitude of one signal level is 0; the other is the same as the amplitude of the

carrier frequency.

A) OOK

B) PSK

C) FSK



19/40

182.

If the bit rate for a 16-QAM signal is 4000 bps, what is the baud rate?

A) 1200

B) 1000

C) 400

D) 300

183.ASK, PSK, FSK, and QAM are examples of ________ conversion.

A) analog-to-analogB) digital-to-digital

C) analog-to-digital

D) digital-to-analog

184.If the bit rate for an FSK signal is 1200 bps, the baud rate is ________.

A) 1200

B) 600

C) 400

D) 300

185.The constellation diagram of BASK has ______ dots.

A) 0

B) 1

C) 2


186.The Federal Communications Commission (FCC) allows ______kHz for each AM station.

A) 20

B) 10

C) 5


187.

How many carrier frequencies are used in BFSK?

A) 2

B) 1

C) 0


188.In _____ transmission, the phase of the carrier signal is modulated to follow the changing voltage level

(amplitude) of the modulating signal.A) AM

B) FM

C) PM


189._________ conversion is the representation of analog information by an analog signal.

A) Analog-to-analog

B) Digital-to-digital

C) Analog-to-digital

D) Digital-to-analog

190.

In _____ transmission, the carrier signal is modulated so that its amplitude varies with the changing

amplitudes of the modulating signal.

A) PM

B) FM

C) AM


191.In QAM, both ________ of a carrier frequency are varied.

A) phase and frequency

B) amplitude and phase

C) frequency and amplitude


192.________ uses two carriers, one in-phase and the other quadrature.


20/40


21/40

C) TDM


202.FDM is an _________technique.

A) digital

B) analog


D) none of the above203.______ can be applied when the bandwidth of a link (in hertz) is greater than the combined bandwidths

of the signals to be transmitted.

A) TDM

B) FDM

C) Both (a) or (b)

D) Neither (a) or (b)

204.

In TDM, the transmission rate of the multiplexed path is usually _______ the sum of the transmission

rates of the signal sources.

A) equal to

B) less than

C) greater than

D) not related to

205.

In a multiplexed system, __ lines share the bandwidth of ____ link.

A) 1; n

B) n; 1

C) 1; 1

D) n; n

206.

_________ utilization is the use of available bandwidth to achieve specific goals.

A) Amplitude

B) Frequency

C) Bandwidth


207.____ is designed to use the high bandwidth capability of fiber-optic cable.

A) WDM

B) FDMC) TDM


208.We can divide ____ into two different schemes: synchronous or statistical.

A) WDM

B) TDM

C) FDM


209.In ________ TDM, each input connection has an allotment in the output even if it is not sending data.

A) isochronous

B) statistical

C) synchronous


210.

In ________ TDM, slots are dynamically allocated to improve bandwidth efficiency.

A) isochronous

B) synchronous

C) statistical


211.

The word ______ refers to the portion of a _______ that carries a transmission.

A) line; channel

B) channel; link

C) link; channel


22/40

D) line; link

212.Which multiplexing technique shifts each signal to a different carrier frequency?

A) FDM

B) TDM

C) Both (a) and (b)


213.

Which multiplexing technique transmits analog signals?A) WDM

B) TDM

C) FDM

D) (a) and (c)

214.________ is the set of techniques that allows the simultaneous transmission of multiple signals across a

single data link.

A) Demodulating

B) Multiplexing

C) Compressing


215.________ can be achieved by using multiplexing; ______ can be achieved by using spreading.

A) Privacy and antijamming; efficiency

B) Privacy and efficiency; antijamming

C) Efficiency; privacy and antijamming

D) Efficiency and antijamming; privacy

216.The ______ technique expands the bandwidth of a signal by replacing each data bit with n bits.

A) DSSS

B) FHSS

C) FDM

D) TDM

217.________ is a digital process that allows several connections to share the high bandwidth of a link.

A) WDM

B) TDM

C) FDM

D) None of the above218.

_______ is a digital multiplexing technique for combining several low-rate channels into one high-rate

one.

A) WDM

B) TDM

C) FDM


219.In ________, we combine signals from different sources to fit into a larger bandwidth.

A) line coding

B) block coding

C) spread spectrum


220.Which multiplexing technique involves signals composed of light beams?

A) WDM

B) FDM

C) TDM


221.When the angle of incidence is _______ the critical angle, the light beam bends along the interface.

A) less than

B) equal to

C) more than



23/40

222.

Transmission media lie below the _______ layer.

A) application

B) transport

C) network

D) physical

223._________ cable consists of an inner copper core and a second conducting outer sheath.

A) Twisted-pairB) Shielded twisted-pair

C) Coaxial

D) Fiber-optic

224.__________ consists of a central conductor and a shield.

A) Twisted-pair

B) Coaxial

C) Fiber-optic


225._______ cable can carry signals of higher frequency ranges than _______ cable.

A) Coaxial; twisted-pair

B) Twisted-pair; fiber-optic

C) Coaxial; fiber-optic


226._________ are used for cellular phone, satellite, and wireless LAN communications.

A) Radio waves

B) Infrared waves

C) Microwaves


227.

The inner core of an optical fiber is _______ in composition.

A) copper

B) glass or plastic

C) bimetallic

D) liquid

228.What is the major factor that makes coaxial cable less susceptible to noise than twisted-pair cable?

A) insulating materialB) inner conductor

C) diameter of cable

D) outer conductor

229.Signals with a frequency below 2 MHz use _______ propagation.

A) line-of-sight

B) sky

C) ground


230.In an optical fiber, the inner core is _______ the cladding.

A) less dense than

B) denser than

C) the same density as

D) another name for

231.

________ cable consists of two insulated copper wires twisted together.

A) Twisted-pair

B) Coaxial

C) Fiber-optic


232.In fiber optics, the signal is _______ waves.

A) radio

B) light


24/40

C) infrared

D) very low-frequency

233.Signals with a frequency above 30 MHz use _______propagation.

A) line-of-sight

B) sky

C) ground

D) none of the above234.A parabolic dish antenna is a(n) _______ antenna.

A) unidirectional

B) bidirectional

C) omnidirectional

D) horn

235.A(n) _______ medium provides a physical conduit from one device to another.

A) unguided

B) guided



236.________ cable is used for voice and data communications.

A) Twisted-pair

B) Coaxial

C) Fiber-optic


237.Signals with a frequency between 2 MHz and 30 MHz use _______ propagation.

A) ground

B) line-of-sight

C) sky


238.Transmission media are usually categorized as _______.

A) determinate or indeterminate

B) fixed or unfixed

C) guided or unguided

D) metallic or nonmetallic239.

________ are used for short-range communications such as those between a PC and a peripheral device.

A) Radio waves

B) Infrared waves

C) Microwaves


240.

_________ media transport electromagnetic waves without the use of a physical conductor.

A) Guided

B) Unguided

C) Either (a) or (b)


241.________ cables are composed of a glass or plastic inner core surrounded by cladding, all encased in an

outside jacket.

A) Twisted-pair

B) Coaxial

C) Fiber-optic


242.Which of the following primarily uses guided media?

A) radio broadcasting

B) satellite communications

C) local telephone system

D) cellular telephone system


25/40


26/40

A) time-division

B) two-dimensional

C) space-division

D) three-dimensional

254.

In a ________ network, two types of addressing are involved: global and local.

A) datagram

B) virtual-circuitC) circuit-switched


255.

In a three-stage space division switch, if N = 200, the number of crosspoints is ______.

A) 40,000

B) less than 40,000

C) greater than 40,000

D) greater than 100,000

256.A ________ network is made of a set of switches connected by physical links, in which each link is divided

into n channels.

A) circuit-switched

B) line-switched

C) frame-switched


257.In a banyan switch, for 8 inputs and 8 outputs, we have _____ microswitches at each stage.

A) 2

B) 3

C) 4

D) 8

258.

In _________, there is no resource allocation for a packet.

A) circuit switching

B) datagram switching

C) frame switching


259.A _________ network is a cross between a circuit-switched network and a datagram network. It has some

characteristics of both.A) packet-switched

B) frame-switched

C) virtual-circuit


260.The most popular technology in time-division switching is called the _________.

A) TSI

B) STI

C) ITS


261.

A switched WAN is normally implemented as a _______ network.

A) virtual-circuit

B) datagram

C) circuit-switched


262.We can say that a packet switch has _______ types of components.

A) four

B) three

C) two


263.In a one-stage space division switch, if N = 200, the number of crosspoints is ______.

A) 20,000


27/40

B) 40,000

C) 30,000

D) 10,000

264.In a banyan switch, for 8 inputs and 8 outputs, we have _____ stages.

A) 2

B) 3

C) 4D) 8

265.

A switch in a datagram network uses a routing table that is based on the ______ address.

A) destination

B) source

C) local


266.

Traditionally, _____ methods of switching have been important.

A) six

B) five

C) four

D) three

267.The network layer in the Internet is designed as a __________ network.

A) circuit-switched

B) datagram

C) virtual-circuit


268.A ________ switch combines space-division and time-division technologies to take advantage of the best

of both.

A) SSS

B) TST

C) TTT


269.In _______, the resources need to be reserved during the setup phase; the resources remain dedicated

for the entire duration of data transfer phase until the teardown phase.

A) frame switchingB) datagram switching

C) circuit switching


270.Based on the Clos criteria, if N = 200, then n must be equal to or greater than ____.

A) 40

B) 30

C) 20

D) 10

271.Circuit switching takes place at the ________ layer.

A) physical

B) data line

C) network

D) transport

272.

A ________ switch combines crossbar switches in several (normally three) stages.

A) multiple path

B) multiple crossbar

C) multistage


273.In _______ there are no setup or teardown phases.

A) circuit switching

B) datagram switching


28/40

C) frame switching


274.We can divide today's networks into ____ broad categories.

A) five

B) four

C) three

D) two275.A ________ switch is a multistage switch with microswitches at each stage that route the packets based

on the output port represented as a binary string.

A) TSI

B) banyan

C) crossbar


276.

The _______ address in the header of a packet in a datagram network normally remains the same during

the entire journey of the packet.

A) destination

B) source

C) local


277.

Based on the Clos criteria, if N = 200, then the minimum number of crosspoints is greater than or equal to

_______.

A) 42,000

B) 20,000

C) 18,000

D) 15,200

278.

The simplest type of switching fabric is the ______ switch.

A) crossbar

B) crosspoint

C) TSI

D) STS

279.To use a cable network for data transmission, we need two key devices: a ______ and a _________

A) CT; CMTSB) CM; CMTS

C) CM; CMS


280.A local telephone network is an example of a _______ network.

A) packet-switched

B) message-switched

C) circuit-switched


281.A traditional cable TV network transmits signals ______.

A) downstream

B) upstream

C) upstream and downstream


282.

The traditional cable TV system used ________cable end to end.

A) twisted-pair

B) fiber-optic

C) coaxial


283.The telephone network is made of ______ major components.

A) 4

B) 3


29/40

C) 2


284.Data from a computer are _______; the local loop handles _______ signals.

A) analog; analog

B) digital; digital

C) digital; analog

D) analog; digital285.The original telephone network, which is referred to as the plain old telephone system (POTS), was an

________ system.

A) analog

B) digital

C) digital as well as analog


286.

The protocol that is used for signaling in the telephone network is called ______.

A) SSS

B) SS7

C) POP


287._______technology is a set of technologies developed by the telephone companies to provide high data

rate transmission.

A) LDS

B) ASL

C) DSL


288.

The local loop has _______ cable that connects the subscriber telephone to the nearest end office.

A) fiber-optic

B) coaxial

C) twisted-pair


289.The second generation of cable networks is called a(n) _________ network.

A) HCF

B) HFCC) CFH


290.The largest portion of the bandwidth for ADSL carries _______.

A) upstream data

B) downstream data

C) control data

D) voice communication

291._______ is suitable for businesses that require comparable upstream and downstream data rates.

A) SDSL

B) ADSL

C) VDSL

D) (b) and (c)

292.

The carrier that handles intra-LATA services is called a(n) _____ .

A) IXC

B) LEC

C) POP


293.

DMT is a modulation technique that combines elements of _______ and _______.

A) FDM; QAM

B) FDM; TDM

C) PSK; FSK


30/40

D) QDM; QAM

294.The carrier that handles inter-LATA services is called a(n) _______.

A) IXC

B) LEC

C) POP


295.

The modern telephone network is now ________.A) digital

B) digital as well as analog

C) analog


296.In an HFC network, the upstream data are modulated using the _______ modulation technique.

A) ASK

B) PCM

C) QAM

D) QPSK

297.

_______ was designed as an alternative to the T-1 line.

A) ADSL

B) HDSL

C) VDSL

D) SDSL

298.HDSL encodes data using _______.

A) 2B1Q

B) 1B2Q

C) 4B/5B

D) 6B/8T

299.In an HFC network, the downstream data are modulated using the _______ modulation technique.

A) PCM

B) QAM

C) PSK

D) ASK

300.

Another name for the cable TV office is the _______.A) head end

B) combiner

C) fiber node

D) splitter

301.The term modem is a composite word that refers to the two functional entities that make up the device: a

signal _______ and a signal _______.

A) demodulator; modulator

B) modulator; demodulator

C) modern; demo


302.The two most common digital services are ________ service and ______.

A) switched/56; DDS

B) switched/56; switched/64

C) DDS; switched 64

D) leased; out-of-band

303.The United States is divided into many _______.

A) IXCs

B) LECs

C) LATAs


304.The standard for data transmission over an HFC network is called _______.


31/40

A) ADSL

B) CMTS

C) DOCSIS

D) MCNS

305.

In ________signaling, a portion of the bandwidth is used for signaling and another portion for data.

A) mixed

B) in-bandC) out-of-band


306.

Telephone companies provide two types of analog services: analog _______ services and analog

_____services.

A) leased; out-of-band

B) out-of-band; in-band

C) switched; in-band

D) switched; leased

307.The HFC network uses _______ cable.

A) coaxial

B) twisted-pair

C) fiber-optic

D) a combination of (a) and (c)

308.In ______signaling, the same circuit is used for both signaling and data.

A) mixed

B) out-of-band

C) in-band


309.

Most popular modems available are based on the ________standards.

A) X-series

B) V-series

C) VX-series


310.Checksums use _________ arithmetic.

A) one's complement arithmeticB) two's complement arithmetic



311.The checksum of 1111 and 1111 is _________.

A) 0000

B) 1111

C) 1110

D) 0111

312.In modulo-11 arithmetic, we use only the integers in the range ______, inclusive.

A) 1 to 10

B) 0 to 10

C) 1 to 11


313.

In cyclic redundancy checking, the divisor is _______ the CRC.

A) one bit less than

B) one bit more than

C) The same size as


314.The ________ between two words is the number of differences between corresponding bits.

A) Hamming rule

B) Hamming code


32/40

C) Hamming distance


315.The _______ of a polynomial is the highest power in the polynomial.

A) range

B) power

C) degree

D) none of the above316.In modulo-2 arithmetic, __________ give the same results.

A) addition and subtraction

B) addition and multiplication

C) addition and division


317.In cyclic redundancy checking, what is the CRC?

A) The quotient

B) The dividend

C) The divisor

D) The remainder

318.Which error detection method consists of just one redundant bit per data unit?

A) CRC

B) Checksum

C) Simple parity check

D) Two-dimensional parity check

319.In _____ coding, we divide our message into blocks, each of k bits, called ___.

A) block; blockwords

B) block; datawords

C) linear; datawords


320.A _____ error means that two or more bits in the data unit have changed.

A) burst

B) double-bit

C) single-bit

D) none of the above321.

Adding 1 and 1 in modulo-2 arithmetic results in _________.

A) 0

B) 1

C) 2


322.

In ________ error correction, the receiver corrects errors without requesting retransmission.

A) onward

B) forward

C) backward


323.If the Hamming distance between a dataword and the corresponding codeword is three, there are _____

bits in error.

A) 5

B) 4

C) 3


324.A simple parity-check code can detect __________ errors.

A) an odd-number of

B) an even-number of

C) two

D) no errors


33/40

325.

The Hamming distance between equal codewords is _________.

A) 0

B) 1

C) n


326.In a linear block code, the _______ of any two valid codewords creates another valid codeword.

A) ANDingB) XORing

C) ORing


327.In ________ error correction, the receiver asks the sender to send the data again.

A) forward

B) backward

C) retransmission


328.We can divide coding schemes into two broad categories: ________ and ______coding.

A) linear; nonlinear

B) block; convolution

C) block; linear


329.In modulo-2 arithmetic, we use only ______.

A) 1 and 2

B) 0 and 1

C) 0 and 2


330.

To guarantee correction of up to 5 errors in all cases, the minimum Hamming distance in a block code

must be ________.

A) 11

B) 6

C) 5


331.

The _____of errors is more difficult than the ______.A) detection; correction

B) correction; detection

C) creation; correction

D) creation; detection

332.In block coding, if k =2 and n =3, we have _______ invalid codewords.

A) 4

B) 8

C) 2


333.

The checksum of 0000 and 0000 is __________.

A) 0000

B) 1111

C) 0111

D) 1110

334.In one's complement arithmetic, if positive 7 is 0111, then negative 7 is ________.

A) 1101

B) 1000

C) 1111


335.In block coding, if n = 5, the maximum Hamming distance between two codewords is ________.

A) 5


34/40

B) 3

C) 2


336.Which error detection method uses one's complement arithmetic?

A) Checksum

B) CRC

C) Simple parity checkD) Two-dimensional parity check

337.

The divisor in a cyclic code is normally called the _________.

A) redundancy

B) degree

C) generator


338.

In modulo-2 arithmetic, we use the ______ operation for both addition and subtraction.

A) OR

B) XOR

C) AND


339.We add r redundant bits to each block to make the length n = k + r. The resulting n-bit blocks are called

_________.

A) codewords

B) datawords

C) blockwords


340.

To guarantee the detection of up to 5 errors in all cases, the minimum Hamming distance in a block code

must be _______.

A) 11

B) 5

C) 6


341.A generator that contains a factor of ____ can detect all odd-numbered errors.

A) xB) 1

C) x + 1


342._______codes are special linear block codes with one extra property. If a codeword is rotated, the result

is another codeword.

A) Convolution

B) Cyclic

C) Non-linear


343.

The Hamming distance between 100 and 001 is ________.

A) 0

B) 1

C) 2


344.In Go-Back-N ARQ, if 5 is the number of bits for the sequence number, then the maximum size of the

receive window must be _____.

A) 1

B) 15

C) 16

D) 31


35/40

345.

In Go-Back-N ARQ, if frames 4, 5, and 6 are received successfully, the receiver may send an ACK _______

to the sender.

A) 6

B) 7

C) 5

D) any of the above

346.

The Stop-And-Wait ARQ, Go-Back-N ARQ, and the Selective Repeat ARQ are for ______ channels.A) noiseless

B) noisy



347.The _________Protocol, adds a simple error control mechanism to the _______Protocol.

A) Selective Repeat ARQ; Go-Back-N ARQ

B) Go-Back-N ARQ; Stop-and-Wait

C) Stop-and-Wait ARQ; Stop-and-Wait


348.

In PPP, the ________ is responsible for establishing, maintaining, configuring, and terminating links.

A) PAP

B) CHAP

C) LCP

D) NCP

349.HDLC is an acronym for _______.

A) Half-duplex digital link combination

B) Host double-level circuit

C) High-duplex line communication

D) High-level data link control

350.In Selective Repeat ARQ, if 5 is the number of bits for the sequence number, then the maximum size of

the receive window must be _____.

A) 1

B) 15

C) 16

D) 31351.

In Go-Back-N ARQ, if 5 is the number of bits for the sequence number, then the maximum size of the send

window must be _____.

A) 1

B) 15

C) 16

D) 31

352.In Stop-and-Wait ARQ, the acknowledgment number always announces in ______ arithmetic the

sequence number of the next frame expected.

A) modulo-m

B) modulo-2

C) modulo-4


353.

In Selective Repeat ARQ, if 5 is the number of bits for the sequence number, then the maximum size of

the send window must be _____.

A) 1

B) 15

C) 16

D) 31

354._______ control refers to a set of procedures used to restrict the amount of data that the sender can send

before waiting for acknowledgment.

A) Flow


36/40

B) Error

C) Transmission


355.In the Go-Back-N Protocol, if the size of the sequence number field is 8, the sequence numbers are in

________ arithmetic,

A) modulo-256

B) modulo- 8C) modulo-2


356.

______ control refers to methods of error detection and correction.

A) Flow

B) Error

C) Transmission


357.In a Go-Back-N ARQ, if the window size is 63, what is the range of sequence numbers?

A) 1 to 63

B) 1 to 64

C) 0 to 63

D) 0 to 64

358.

Both Go-Back-N and Selective-Repeat Protocols use a _________.

A) sliding window

B) sliding frame

C) sliding packet


359.

In _________, the configuration is balanced. The link is point-to-point, and each station can function as a

primary and a secondary.

A) ARM

B) ABM

C) NBM

D) NRM

360.Byte stuffing means adding a special byte to the data section of the frame when there is a character with

the same pattern as the ______.A) trailer

B) flag

C) header


361.The ______ Protocol has neither flow nor error control.

A) Selective-Repeat ARQ

B) Go-Back-N ARQ

C) Stop-and-Wait

D) Simplest

362.

The most common protocol for point-to-point access is the Point-to-Point Protocol (PPP), which is a

_________protocol.

A) byte-oriented

B) bit-oriented

C) character-oriented


363.For Stop-and-Wait ARQ, for 10 data packets sent, _______ acknowledgments are needed.

A) less than 10

B) more than 10

C) exactly 10


364._________framing uses two categories of protocols: character-oriented and bit-oriented.


37/40

A) Standard

B) Fixed-size

C) Variable-size


365.

_______ control refers to a set of procedures used to restrict the amount of data that the sender can send

before waiting for acknowledgment.

A) FlowB) Error

C) Transmission


366.In a ________ protocol, the data section of a frame is a sequence of characters.

A) bit-oriented

B) character-oriented



367.In _______ framing, there is no need for defining the boundaries of frames.

A) standard

B) fixed-size

C) variable-size


368.The _______Protocol has both flow control and error control.

A) Stop-and-Wait

B) Selective-Repeat ARQ

C) Go-Back-N ARQ

D) both (b) and (c)

369.

In _________, the station configuration is unbalanced. We have one primary station and multiple

secondary stations.

A) ARM

B) NBM

C) NRM

D) ABM

370.

In a _________ protocol, the data section of a frame is a sequence of bits.A) bit-oriented

B) byte-oriented



371.In ________ framing, we need a delimiter (flag) to define the boundary of two frames.

A) standard

B) fixed-size

C) variable-size


372.

High-level Data Link Control (HDLC) is a _______ protocol for communication over point-to-point and

multipoint links.

A) byte-oriented

B) bit-oriented

C) character-oriented


373.Bit stuffing means adding an extra 0 to the data section of the frame when there is a sequence of bits with

the same pattern as the ________.

A) trailer

B) flag

C) header



38/40

374.

In the _________Protocol, if no acknowledgment for a frame has arrived, we resend all outstanding

frames.

A) Go-Back-N ARQ


C) Stop-and-Wait ARQ


375.

The Simplest Protocol and the Stop-and-Wait Protocol are for ______ channels.A) noiseless

B) noisy



376.The _______Protocol has flow control, but not error control.


B) Stop-and-Wait

C) Simplest

D) Go-Back-N ARQ

377.

In Stop-and-Wait ARQ, we use sequence numbers to number the frames. The sequence numbers are

based on __________arithmetic.

A) modulo-m

B) modulo-2

C) modulo-4


378.In the _____ Protocol, the sender sends its frames one after another with no regard to the receiver.

A) Simplest


C) Stop-and-Wait

D) Go-Back-N ARQ

379._________control in the data link layer is based on automatic repeat request, which is the retransmission

of data.

A) Flow

B) Error

C) TransmissionD) none of the above

380.

In PPP, _______ is a three-way hand-shaking authentication protocol in which the password is kept secret;

it is never sent online.

A) PAP

B) LCP

C) NCP

D) CHAP

381.In PPP, ________ is a simple authentication procedure with a two-step process:

A) CHAP

B) PAP

C) LCP

D) NCP

382.

In the _________ protocol we avoid unnecessary transmission by sending only frames that are corrupted.


B) Stop-and-Wait ARQ

C) Go-Back-N ARQ


383.

In ________ protocols, we use ________.

A) byte-oriented; bit stuffing

B) bit-oriented; bit stuffing

C) character-oriented; bit stuffing


39/40


384.In the _____ Protocol, the sender sends one frame, stops until it receives confirmation from the receiver,

and then sends the next frame.

A) Simplest

B) Stop-and-Wait

C) Selective-Repeat ARQ

D) Go-Back-N ARQ385.Stop-and-Wait ARQ is a special case of Go-Back-N ARQ in which the size of the send window is ___.

A) 1

B) 2

C) 8


386.ARQ stands for _______.

A) Acknowledge repeat request

B) Automatic retransmission request

C) Automatic repeat quantization

D) Automatic repeat request

387._______ in the data link layer separates a message from one source to a destination, or from other

messages going from other sources to other destinations.

A) Controlling

B) Framing

C) Digitizing


388.Data link control deals with the design and procedures for ______ communication.

A) node-to-node

B) process-to-process

C) host-to-host


389.

In _________ protocols, we use ________.

A) bit-oriented; character stuffing

B) character-oriented; bit stuffing

C) character-oriented; byte stuffingD) none of the above


40/40

forouzan qanda

Documents