The correct answer for each question is indicated by

Trắc nghiệm truyền số liệu giúp bạn nắm rõ một số nội dung quan trọng của chương trình học, tài liệu bằng tiếng anh nên giúp bạn tạo một nền tản tiếng anh chuyên nghành khá tốt. với cacsp phần của tài liệu được lấy tự bộ sách chuẩn quốc tế giúp bạn làm quen với bộ giao thức và phương thức hoạt động của mạng LAN và Wan

Chapter 1:

The correct answer for each question is indicated by a

1 CORRECT The _ is the physical path over which a message travels.

2 INCORRECT The information to be communicated in a data communications system is the _.

3 CORRECT Frequency of failure and network recovery time after a failure are measures of the _ of a network.

4 INCORRECT An unauthorized user is a network _ issue.

5 INCORRECT Which topology requires a central controller or hub?

6 CORRECT Which topology requires a multipoint connection?

7 CORRECT Communication between a computer and a keyboard involves transmission.

8 INCORRECT A television broadcast is an example of _ transmission.

9 INCORRECT A _ connection provides a dedicated link between two devices.

1

0 INCORRECT

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

This was the first network.

1 CORRECT Which organization has authority over interstate and international commerce in the

communications field?

1 CORRECT

Data flow between two devices can occur in a _ way

22 INCORRECT In a connection, two and only two devices are connected by a dedicated link.

2

3 INCORRECT

In a connection, three or more devices share a link

4 INCORRECT

refers to the physical or logical arrangement of a network

25 CORRECT Devices may be arranged in a _ topology.

26 INCORRECT A _ is a data communication system within a building, plant, or campus, or between nearbybuildings.

27 INCORRECT A is a data communication system spanning states, countries, or the whole world.

8 INCORRECT

is a collection of many separate networks

29 CORRECT There are Internet service providers.

3

0 INCORRECT

A is a set of rules that governs data communication

1 INCORRECT

is an idea or concept that is a precursor to an Internet standard

CHAPTER 2:

The correct answer for each question is indicated by a

1 INCORRECT The Internet model consists of _ layers.

2 INCORRECT The process-to-process delivery of the entire message is the responsibility of the _ layer.

3 INCORRECT The _ layer is the layer closest to the transmission medium.

4 CORRECT Mail services are available to network users through the _ layer.

5 INCORRECT As the data packet moves from the upper to the lower layers, headers are _.

6 INCORRECT The _ layer lies between the network layer and the application layer.

7 INCORRECT Layer 2 lies between the physical layer and the _ layer.

8 INCORRECT When data are transmitted from device A to device B, the header from A's layer 4 is read by B's _ layer.

9 INCORRECT The _ layer changes bits into electromagnetic signals.

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

1

2 INCORRECT

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

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

1 INCORRECT When a host on network A sends a message to a host on network B, which address does the router

look at?

20 INCORRECT To deliver a message to the correct application program running on a host, the _ address must be consulted.

2

1 INCORRECT

IPv6 has _ -bit addresses

22 CORRECT ICMPv6 includes _.

26 CORRECT The Internetworking Protocol (IP) is a protocol.

27 INCORRECT _ is a process-to-process protocol that adds only port addresses, checksum error control, and length information to the data from the upper layer.

2

8 INCORRECT

provides full transport layer services to applications

29 INCORRECT The address, also known as the link address, is the address of a node as defined by its LAN or WAN.

CHAPTER 3:

The correct answer for each question is indicated by a

1 INCORRECT Before data can be transmitted, they must be transformed to .

A )periodi

c signals

B )electromagnet

ic signals

C )aperiodi

c signals

D )low-frequenc

y sin

e waves

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

A )1

Hz

B )100Hz

C )1KHz

D )1MHz

3 INCORRECT In a frequency-domain plot, the horizontal axis measures the .

A )pea

k amplitude

B )frequency

C )phase

D )slope

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

A )signalamplitude

B )frequency

C )phase

D )time

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

A )5KHz

B )10KHz

C )47KHz

D )57KHz

6 INCORRECT What is the bandwidth of a signal that ranges from 1 MHz to 4 MHz?

A )4MHz

B )1KHz

C )3MHz

D )non

e ofth

e above

7 INCORRECT As frequency increases, the period .

A )decreases

B )increases

C )remain

s th

e same

D )doubles

8 INCORRECT 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 )th

e sam

e as

D )indeterminat

e from

9 INCORRECT A sine wave is .

A )periodi

c an

d continuous

B )aperiodi

c an

d continuous

C )periodi

c an

d discrete

D )aperiodi

c an

d discrete

1

0 INCORRECT

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

A )2B )1C )-2

D )betwee

n -2an

d 2

iszer

B )Pe2qual

s

P1

C )Pis 2muc

h largertha

n

P1

D )Pis 2muc

h smallertha

B )Distortion

C )Noi

D )Decibel

B )Distortion

C )Noise

D )Decibel

B )Distortion

C )Noise

D )Decibel

1

5 CORRECT

When propagation speed is multiplied by propagation time, we get the

A )throughput

B )wavelengt

h ofth

e signal

C )distortio

n fa

D )distance

a sign

al orbi

t ha

s traveled

1

6 INCORRECT

Data can be

A )analog

B )digital

C )(a) o

r (b)

D )non

e ofth

e above

7 INCORRECT

_ data are continuous and take continuous values

A )analog

B )digital

C )(a) o

r (b)

D )non

e ofth

e above

1

8 INCORRECT

_ data have discrete states and take discrete values

A )Analog

B )Digita

C )(a) o

r (b)

D )Non

e ofth

e above

1

9 INCORRECT

Signals can be

A )analog

B )digital

C )either(a) or(b)

D )neither(a) nor(b)

20 INCORRECT _ signals can have an infinite number of values in a range.

A )Analog

B )Digital

C )(a) o

r (b)

D )Non

e ofth

e above

2

1 INCORRECT

_ signals can have only a limited number of values

A )Analog

B )Digita

C )(a) o

r (b)

D )Non

e ofth

e above

22 INCORRECT Frequency and period are .

A )inverseofeac

h other

B )proportionaltoeachother

C )thesame

D )non

e ofth

e above

2

3 INCORRECT

is the rate of change with respect to time

A )Amplitude

B )Time

C )Frequency

D )Voltage

2

4 INCORRECT

_ describes the position of the waveform relative to time 0

A )Frequ

B )Phase

C )Amplitude

D )Voltage

25 INCORRECT A sine wave in the domain can be represented by one single spike in the _ domain.

A )time;

frequency

B )frequency;

time

C )time

; phase

D )phase

; time

26 INCORRECT A _ sine wave is not useful in data communications; we need to send a _ signal.

A )composite;

single-frequency

B )single-frequency;

composite

C )single-frequency;

double-frequency

D )non

e ofth

e above

27 INCORRECT The _ of a composite signal is the difference between the highest and the lowest frequencies contained in that signal.

A )frequency

B )period

C )bandwidth

D )amplitude

2

8 INCORRECT

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

A )digit

B )analog

C )either(a) or(b)

D )neither(a) nor(b)

29 INCORRECT Baseband transmission of a digital signal is possible only if we have a channel.

A )low-pass

B )bandpass

C )lowrate

D )hig

3

0 INCORRECT

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

A )low-pass

B )bandpass

C )lowrate

D )highrate

3

1 INCORRECT

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

A )noisy

B )noiseless

C )bandpass

D )low-pass

3

2 INCORRECT

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

A )noisy

B )noiseless

C )bandpass

D )low-pass

3 CORRECT

_ can impair a signal

A )Attenuation

B )Distortion

C )Noise

D )All ofth

e above

3

4 INCORRECT

The _ product defines the number of bits that can fill the link

A )bandwidth-period

B )frequency-amplitude

C )bandwidth-delay

D )delay-amplitude

CHAPTER 4:

The correct answer for each question is indicated by a

1 INCORRECT Unipolar, bipolar, and polar encoding are types of _ encoding.

A )line

B )block

C )NRZ

D )Manchester

2 CORRECT _ encoding has a transition at the middle of each bit.

A )RZ

B )Manchester

C )DifferentialManchester

D )All th

e above

3 INCORRECT _ encoding has a transition at the beginning of each 0 bit.

A )RZ

B )Manchester

C )DifferentialManchester

D )All th

e above

4 CORRECT PCM is an example of _ conversion.

A )digital-to-digital

B )digital-to-analog

C )analog-to-analog

D )analog-to-digital

5 CORRECT If the frequency spectrum of a signal has a bandwidth of 500 Hz with the highest frequency at 600 Hz, what should be the sampling rate, according to the Nyquist theorem?

A )20

0 samples/

s

B )50

0 samples/

s

C )100

0 samples/

s

D )120

0 samples/

s

6 CORRECT The Nyquist theorem specifies the minimum sampling rate to be _.

A )equa

l toth

e lowes

t frequenc

y of

a signal

B )equa

l toth

e highes

t frequenc

y of

a signal

C )twic

e th

e band

h of

a signal

D )twic

e th

e highes

t frequenc

y of

a signal

7 INCORRECT Which of the following encoding methods does not provide for synchronization?

A )NRZ-L

B )RZ

C )NRZ-I

D )Manchester

8 CORRECT Which encoding method uses alternating positive and negative values for 1s?

A )NRZ-I

B )RZ

C )Manchester

D )AMI

9 CORRECT Which quantization level results in a more faithful reproduction of the signal?

A )2B )8C )16

D )32

1

0 CORRECT

Block coding can help in _ at the receiver

A )Synchronizatio

B )Erro

r detection

C )Attenuation

D )(a) and(b)

1

1 INCORRECT

In _ transmission, bits are transmitted simultaneously, each across its own wire

A )Asynchronou

s serial

B )Synchronou

s seri

C )Parallel

D )(a) and(b)

1

2 CORRECT

In _ transmission, bits are transmitted over a single wire, one at a time

A )asynchronou

s serial

B )synchronou

s serial

C )parallel

D )(a)

1

3 INCORRECT

In _ transmission, a start bit and a stop bit frame a character byte

A )asynchronou

s serial

B )synchronou

s serial

C )parallel

D )(a) and(b)

4 INCORRECT

In asynchronous transmission, the gap time between bytes is _

A )fixed

B )variable

C )a functio

n ofth

e dat

a rate

D )zero

1

5 CORRECT

_ conversion involves three techniques: line coding, block coding, and scrambling

A )Analog-to-digital

B )Digital-to-an

C )Analog-to-analog

D )Digital-to-digital

1

6 INCORRECT

is the process of converting digital data to a digital signal

A )Bloc

k coding

B )Lin

e coding

C )Scrambling

D )Non

e ofth

e above

1

7 INCORRECT

_ provides redundancy to ensure synchronization and inherent error detection

A )Bloc

k coding

B )Lin

e coding

C )Scrambling

D )Non

e ofth

e above

1 INCORRECT is normally referred to as mB/nB coding; it replaces each m-bit group with an n-bit

group

A )Bloc

k coding

B )Lin

e coding

C )Scrambling

D )Non

e ofth

e above

1

9 INCORRECT

provides synchronization without increasing the number of bits

A )Scrambling

B )Lin

e codin

C )Bloc

k coding

D )Non

e ofth

e above

20 INCORRECT Two common scrambling techniques are .

A )NRZan

d RZ

B )AM

I an

d NRZ

C )B8Z

S an

d HDB3

D )Manch

r an

d differentialManchester

2

1 INCORRECT

The most common technique to change an analog signal to digital data is called

A )PAL

B )PCM

C )sampling

D )non

e ofth

e above

22 INCORRECT The first step in PCM is .

A )qua

B )modulation

C )sampling

D )non

e ofth

e above

2

3 INCORRECT

There are three sampling methods:

A )quantized, sampled, an

d ideal

B )idea

l, sa

mpled, an

d flat-top

C )idea

l, natural, an

d flat-top

D )non

e ofth

e above

; PCM

B )PCM

; DM

CD

; CM

D )non

e ofth

e above

25 INCORRECT While there is (are) only _ way(s) to send parallel data, there is (are) three subclass(es) of serial transmission.

A )one

; two

B )two

; three

C )one

; three

D )non

e ofth

e above

26 INCORRECT 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

D )non

e ofth

e above

27 INCORRECT 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 )syn

B )asynchronous

C )isochronous

D )non

e ofth

e above

Ba

ynchronous

C )isochronous

D )non

e ofth

e above

29 INCORRECT A _ digital signal includes timing information in the data being transmitted.

A )self-synchronizing

B )self-modulated

C )sel

f-D )non

e ofth

e above

B )base

C )line

D )non

e ofth

e above

1 INCORRECT

The rate defines the number of data elements sent in 1s; the rate is the number

of signal elements sent in 1s

A )data

; signal

B )signal

; data

C )baud

; bit

D )non

e ofth

e above

3

2 INCORRECT

The signal rate is sometimes called the rate

A )baud

B )bit

Cs

gnal

D )non

e ofth

e above

3

3 INCORRECT

The data rate is sometimes called the _ rate

A )baud

B )bit

C )signal

D )non

e ofth

e above

3

4 INCORRECT

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

A )polar

B )bipolar

C )unipolar

D )all ofth

e above

B )bipolar

C )unipolar

D )all ofth

e above

3

6 INCORRECT

In _, the level of the voltage determines the value of the bit

A )NRZ-I

B )NRZ-L

C )bot

h (a) an

d (b)

D )neither(a) nor(b)

3

7 INCORRECT

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

AN

Z-I

B )NRZ-L

C )bot

h (a) an

d (b)

D )neither(a) nor(b)

3

8 INCORRECT

The idea of RZ and the idea of NRZ-L are combined into the scheme

A )Manchester

B )differentialManchester

C )bot

h (a) an

d (b)

D )neither(a) nor(b)

3

9 INCORRECT

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

A )Manchester

B )differentialManchester

C )bot

h (a) an

d (b)

Dn

ther(a) nor(b)

4

0 INCORRECT

In _ encoding, the duration of the bit is divided into two halves The voltage remains at onelevel 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 )differentialManchester

C )bot

h (a) an

d (b)

D )neither(a) nor(b)

1 INCORRECT

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 )differentialManchester

C )bot

h (a) an

d (b)

D )neither(a) nor(b)

B )bau

d transfer

C )synchronization

D )non

e ofth

e above

4

3 INCORRECT

The minimum bandwidth of Manchester and differential Manchester is that of NRZ

A )th

e sam

e as

B )twice

C )th