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Nwc203c

Total questions: 125

Worksheet time: 1hrs 7mins

Name
Class
Date
1.

Which of the following networks use store-and-forward switching operation?

a)

Computer networks

b)

Telegraph networks

c)

Telephone networks

d)

Wireless Networks

2.

There are similarities between message switching and packet switching. Which of following that applies to packet switching but not to message switching?

a)

Variable length of information block

b)

Supporting multiple applications

c)

Store-and-forward

d)

All of the above

3.

Which of the following networks can be connection-oriented?

a)

Telegraph networks

b)

Computer networks

c)

Telephone networks

d)

All of the above

4.

A protocol is a set of precise and unambiguous rules that governs

a)

How two or more communicating entities in a layer are to interact

b)

Messages that can be sent and received

c)

Actions that are to be taken when a certain event occurs

d)

All of the above

5.

DNS is a domain-name-service that responds to queries of domain name to IP address or IP address to domain name. DNS uses services provided by

a)

TCP

b)

UDP

c)

HTTP

d)

None of the above

6.

A network used to join the individual networks at different sites into one extended network is called

a)

PAN

b)

LAN

c)

SAN

d)

VPN

7.

Upon receipt of a bad segment, UDP?

a)

It does flow control

b)

It does not do flow and error control

c)

It does error control

d)

Retransmission

8.

Which of following protocol is HTTP built upon?

a)

IP

b)

TCP

c)

UDP

d)

SMTP

9.

Which of following requirements are necessary for packet networks to support multiple and diverse applications?

a)

Transfer arbitrary message size

b)

Low delay for interactive applications

c)

Packets have maximum length

d)

All of the above

10.

What was the concern of the telephone system that motivated the ARPANET design?

a)

Scalability

b)

Vulnerability

c)

Efficiency

d)

None of the above

11.

Which of the following is an application layer protocol?

a)

HTTP

b)

UDP

c)

DNS

d)

TCP

12.

Which of the following are features of ARPANET design?

a)

Connectionless packet transmission

b)

Routing tables at the packet switches

c)

Destinations identified by unique addresses

d)

All of the above

13.

Bluetooth is an example of

a)

Local Area Network

b)

Wide Area Network

c)

Metropolitan Area Network

d)

Personal Area Network

14.

In the layer hierarchy as the data packet moves from the upper to the lower layers, headers are

a)

Removed

b)

Modified

c)

Added

d)

Rearranged

15.

The ________ is the physical path over which a message travels

a)

Protocol

b)

Route

c)

Medium

d)

Path

16.

Three or more devices share a link in ________ connection

a)

Unipoint

b)

Multipoint

c)

Point to Point

d)

None of the above

17.

Which of the following is true for Transport Control Protocol

a)

Connection oriented

b)

Process to Process

c)

Transport layer protocol

d)

Connectionless

18.

Which OSI layer is responsible for providing end-to-end communication with reliable service?

a)

Transport layer

b)

Network layer

c)

Session layer

d)

Data link layer

19.

Which OSI layer is responsible for dividing the transmitted bit stream into frames?

a)

Network layer

b)

Transport layer

c)

Application layer

d)

Data link layer

20.

Which OSI layer is responsible for determining which route through the network to use?

a)

Network layer

b)

Data link layer

c)

Transport layer

d)

None of the above

21.

Which feature does the data link layer and transport layer have in common?

a)

Medium access control

b)

All of the above

c)

Congestion control

d)

Flow control

22.

Which protocol glues the network of networks together as the Internet?

a)

TCP

b)

UDP

c)

IP

d)

None of the above

23.

In a LAN, which address is used to transfer frames to appropriate destination?

a)

IP address

b)

Physical address

c)

Domain name

d)

None of the above

24.

Suppose an application layer entity wants to send an L-byte message to its peer process, using an existing TCP connection. The TCP segment consists of the message plus 20 bytes of header. The segment is encapsulated into an IP packet that has an additional 20 bytes of header. The IP packet in turn goes inside an Ethernet frame that has 18 bytes of header and trailer. What is the bandwidth utilization in terms of the percentage of the transmitted bits in the physical layer corresponds to message information if L = 500 bytes?

a)

100%

b)

70%

c)

90%

d)

80%

25.

Of the following services, which service(s) does the IP layer provides?

a)

Error control

b)

Flow control

c)

Connection-based data transfer

d)

None of the above

26.

Which of the following is true about the ways in which the OSI reference model and TCP/IP reference model differ.

a)

They differ in the number of layers

b)

TCP/IP model does not have presentation layer, but OSI model has

c)

TCP/IP model does not have session layer, but OSI model has

d)

All of the above

27.

Which of following statements is true about how the data link layer and transport layer differ?

a)

Data link layer is concerned with framing and the transport layer is not

b)

Data link layer is concerned with flow control and the transport layer is not

c)

Data link layer is concerned with multiplexing and the transport layer is not

d)

All of the above

28.

This layer is an addition to OSI model

a)

Application layer

b)

Presentation layer

c)

Session layer

d)

Presentation layer and Session layer

29.

The functionalities of presentation layer includes

a)

Data compression

b)

Data encryption

c)

Data decryption

d)

All of the above

30.

Which of the following applications would you select TCP protocol for?

a)

File transfer

b)

Domain name service

c)

Web browsing

d)

None of the above

31.

In BSD socket API, which type of socket is used to create a TCP socket?

a)

SOCK_STREAM

b)

SOCK_RAW

c)

SOCK_DGRAM

d)

None of the above

32.

In BSD socket API, which type of socket is used to create a UDP socket?

a)

SOCK_STREAM

b)

SOCK_DGRAM

c)

SOCK_RAW

d)

None of the above

33.

In BSD socket API, which system call is used to assign a network address to the socket?

a)

listen()

b)

None of the above

c)

connect()

d)

bind()

34.

In BSD socket API, if a client knows the server name but not server's network address, what system call should the client use to get server's network address?

a)

Connect()

b)

gethostbyname()

c)

None of the above

d)

gettimeofday()

35.

In a transmission system, which of the following statement is true for a receiver

a)

Receives energy from medium

b)

Converts information into signal suitable for transmission

c)

Converts received signal suitable for delivery to user

d)

All of the above

36.

In digital transmission, long distance digital communications require the use of a generator to recover original data sequence and re-transmits on next segment

a)

True

b)

False

37.

In twisted pair, a category 5 UTP cable can support a data rate of up to 16MHz

a)

True

b)

False

38.

Which of the following statement is true for optical fiber

a)

Plentiful bandwidth for new services

b)

Dominates long distance transmission

c)

Distance less of a cost factor in communications

d)

All of the above

39.

Which of the following are advantages of optical fiber

a)

Noise immunity

b)

No corrosion

c)

Extremely low bandwidth

d)

Wavelength dependency

40.

Given a 7-bit information frame (0, 1, 0, 1, 1, 0, 1), what is the even parity bit?

a)

1

b)

0

c)

None of the above

41.

Which of following statements are true for single-bit parity error detection? (2 answers)

a)

It can detect all single bit errors in an information frame

b)

It can detect all double bit errors in an information frame

c)

It can detect all tripe bit errors in an information frame

d)

None of the above

42.

Which of following statements are true for two-dimensional parity error detection?

a)

It can detect all single bit errors in an information frame

b)

It can correct all single bit errors in an information frame

c)

It can detect all double bit errors in an information frame

d)

All of the above

43.

What is the binary sequence that corresponds to polynomial code X^3 + x^2 + 1?

a)

1110

b)

0111

c)

1101

d)

111

44.

Block codes are generated using _____.

a)

Generator matrix

b)

Generator polynomial

c)

Both of the mentioned

d)

None of the mentioned

45.

Which of the following is true for two-dimensional parity check

a)

Arrange information in rows

b)

More parity bit to improve coverage

c)

Arrange information in columns

d)

Add multiple parity bits to each column

46.

Using Euclidean Division, what will be the remainder of 70 by 999 where 70 is the divisor and 999 is the dividend

a)

17

b)

14

c)

21

d)

19

47.

ARQ protocols combine error detection, retransmission and sequence numbering to provide reliability

a)

True

b)

False

48.

Perform the bit stuffing procedure for the following binary sequence: 1101111111011111110101. What is the outcome?

a)

110111110110111110110101

b)

110111111101111111010100

c)

0010000000100000001010

d)

None of the above

49.

Perform bit de-stuffing for the following sequence: 11101111101111100111110.

a)

11101111111111011111

b)

00010000010000011000001

c)

11100111111110011111

d)

None of the above

50.

PPP is a data link protocol for point-to-point lines in Internet. Its framing is based on which of the following?

a)

Byte stuffing

b)

Bit stuffing

c)

Word stuffing

d)

None of the above

51.

HDLC is another data link control protocol widely in use. Its framing is based on which of the following?

a)

Byte stuffing

b)

Bit stuffing

c)

Word stuffing

d)

None of the above

52.

Which of following statements are true for HDLC?

a)

supports various data transfer modes

b)

supports multi-point links and point to point links

c)

implements error control and flow control mechanisms

d)

All of the above

53.

In PPP authentication, which of the following is true for Challenge-Handshake Authentication Protocol (CHAP)

a)

Initiator and authenticator share a secret key

b)

Initiator must send ID and password

c)

After several attempts, LCP closes link

d)

Authenticator can reissue challenge during session

54.

In error detection and loss recovery, which of the following statement is correct

a)

Frames may undergo errors in transmission

b)

CRCs detect errors and such frames treated as lost

c)

Frames lost due to loss-of-synchronization or receiver buffer overflow

d)

All of the above

55.

In multiplexing, Last IN First Out (LIFO) is used to determine the order of packet transmission

a)

True

b)

False

56.

Generic Framing Procedure (GFP) allows the implementation of multiple transport modes that may coexist within the same transport channel

a)

True

b)

False

57.

In Generic Framing Procedure (GFP), which of the following sentences are correct

a)

GFP uses a variation of HEC-based self delineation technique

b)

GFP provides flexible encapsulation framework that supports either a fixed or variable length frame structure

c)

GFP uses an explicit payload length indicator provided in its frame header to accommodate variable length PDUs

d)

GFP rely on byte-stuffing mechanism to delineate protocol data units (PDUs)

58.

What is the primary function of medium access control?

a)

It is to deal with the flow control of a shared communication link.

b)

It is to minimize or eliminate the incidence of collisions of a shared communication link.

c)

It is to deal with the congestion control of a shared communication link.

d)

None of the above

59.

What is the primary benefit provided by the Slotted ALOHA compared to ALOHA?

a)

Higher maximum throughput

b)

Lower access delay

c)

Both of the above

d)

None of the above

60.

What is the vulnerable period of collisions in ALOHA?

a)

Round-trip propagation delay

b)

One frame transmission time

c)

Two frame transmission time

d)

None of the above

61.

What is the vulnerable period of collisions in Slotted ALOHA?

a)

Round-trip propagation delay

b)

One frame transmission time

c)

Two frame transmission time

d)

None of the above

62.

What is the vulnerable period of collisions in Carrier Sense Multiple Access (CSMA)?

a)

One frame transmission time

b)

None of the above

c)

Round-trip propagation delay

d)

One propagation delay

63.

The primary function of Media Access Control is to minimize or eliminate the instance of the collisions to achieve a reasonable utilization of the medium

a)

True

b)

False

64.

In media sharing techniques, which of the following are channelization approaches

a)

Data Division Multiple Access

b)

Time Division Multiple Access

c)

Code Division Multiple Access

d)

Frequency Division Multiple Access

65.

Corresponding box of Carrier Sense Multiple Access/Collision Detection can be replaced by one of the

a)

Persistent process

b)

P-persistent process

c)

Non-persistent process

d)

I-persistent process

66.

Random access is also called the

a)

Controlled access

b)

Channelization

c)

Authentication

d)

Contention methods

67.

In Carrier Sense Multiple Access (CSMA), possibility of collision still exist because of

a)

Propagation delay

b)

Collision delay

c)

Transmit delay

d)

None of the above

68.

Polling is a scheduling approach for dynamic medium access control. Which of following statements are correct?

a)

Polling can provide bounds on access delay to the shared medium

b)

All of the above

c)

Polling can provide fairness through regulated access opportunities

d)

Polling performance can deteriorate with large delay-bandwidth product

69.

In a collision-free reservation system that has a large number of light-traffic stations, and the delay-bandwidth product is larger than 1. Which of following MAC protocol is a good fit for stations to reserve mini-slots?

a)

1-persistent CSMA

b)

Slotted ALOHA

c)

CSMA/CD

d)

None of the above

70.

In Carrier Sense Multiple Access with collision detection (CSMA-CD), how long will it take a collision to be detected and resolved?

a)

Round-trip propagation delay

b)

One propagation delay

c)

One frame transmission time

d)

None of the above

71.

Suppose that the ALOHA protocol is used to share a 56 kbps satellite channel. Suppose that frames are 1000 bits long. What is the maximum throughput of the system in number of frames per second.

a)

1 frame per second

b)

10 frames per second

c)

100 frames per second

d)

None of the above

72.

Consider building a CSMA/CD network running at 1Gbps over a 1-km cable. The signal speed in the cable is 200,000 km/sec. What is the minimum frame size?

a)

64 Bytes

b)

640 Bytes

c)

1250 Bytes

d)

None of the above

73.

In media access control, which of the following statements are true for Channelization

a)

Inflexible in allocating bandwidth to users with different requirements

b)

Does not scale well to large numbers of users

c)

Widely used in internet traffic

d)

Inefficient for bursty traffic

74.

In BSD socket API, which call is usually used for transmitting data in the connectionless mode?

a)

accept()

b)

connect()

c)

sendto()

d)

None of the above

75.

Which of following statement about TCP/UDP sockets is wrong?

a)

TCP socket is stream oriented

b)

UDP socket is block oriented

c)

TCP is faster than UDP

d)

All of the above

76.

Which of following are commonly used as digital communication medium?

a)

Coaxial cable

b)

All of the above

c)

Twisted pair

d)

Optical fiber

77.

Consider a network link that has distance of 100 meters, and signal traverses at the speed of light in cable 2.5 x 10^8 meters per second. The link has transmission bandwidth of 100 megabits/second (100 x 10^6 bits per second). The packet size is 400 bits. What is the signal propagation delay?

a)

4 x 10^-6 seconds

b)

4 x 10^-7 seconds

c)

4 x 10^-9 seconds

d)

None of the above

78.

Consider a network link that has distance of 100 meters, and signal traverses at the speed of light in cable 2.5 x 10^8 meters per second. The link has transmission bandwidth of 100 megabits/second (100 x 10^6 bits per second). The packet size is 400 bits. What is the packet transmission delay?

a)

None of the above

b)

4 x 10^-7 seconds

c)

4 x 10^-6 seconds

d)

4 x 10^-9 seconds

79.

An API allows application programs to access certain resources through a predefined interface?

a)

True

b)

False

80.

In transport protocol, which of the following statements is true for User Datagram Protocol

a)

It enables best-effort connectionless transfer of individual block of information

b)

It enables connection-oriented reliable transfer of individual block of information

c)

It enables best-effort connectionless reliable transfer of a stream of bytes

d)

None of the above

81.

Which of the following sentences are true for connectionless stream mode of service (3 answers)

a)

No setup overhead and delay

b)

Send/receive to/from multiple peer processes

c)

Destination address with each block

d)

Multiple write/read between peer processes

82.

In transmission delay, in order to reduce the number of bits in a message we use data compression

a)

True

b)

False

83.

Which of the following is true of data compression algorithms (3 answers)

a)

Modify data headers

b)

Recover information approximately

c)

Represent the information using fewer bits

d)

Recover original information exactly

84.

Assume bit errors occur at random. If each bit has 50% probability to be in error by transmission. What is the probability of a four-bit frame to be in error by transmission?

a)

1/4

b)

1/8

c)

1/16

d)

None of the above

85.

A cyclic code can be generated using __________.

a)

Generator matrix

b)

Generator polynomial

c)

Both of the mentioned

d)

None of the mentioned

86.

Polynomial codes are implemented using shift register circuits

a)

True

b)

False

87.

What is the binary equivalent of the following polynomial arithmetic x7 + x6 + x5 + x2 + 1

a)

11101101

b)

11100101

c)

11100111

d)

11011101

88.

Given an information polynomial code I(x) = X^7 + x^6 + x^1 + 1, which is its corresponding per-bit information frame?

a)

None of the above

b)

11000011

c)

10100010

d)

01100011

89.

What is the remainder obtained by dividing x^7 + x^5 + 1 by the generator polynomial x^3 + 1?

a)

x^2 + 1

b)

x^2 + x + 1

c)

None of the above

d)

x^2 + x

90.

Given a generator polynomial g(x) = x^3 + x + 1. Consider the information sequence 1001. By CRC method, what is the resulted codeword for transmission?

a)

1001111

b)

1001000

c)

1001110

d)

1010110

91.

Which of following generator polynomial can detect all single bit errors in an information frame?

a)

g(x) = x

b)

g(x) = x^2

c)

g(x) = x + 1

d)

All of the above

92.

Internet protocols use check bits to detect errors, instead of using CRC polynomial. The primary rationale is

a)

Strength of error detection capability

b)

Simplicity of implementation

c)

CRC polynomial cannot work for Internet protocols

d)

None of the above

93.

The two basic approaches in error control are error prevention and detection, and error correction and re-transmission

a)

True

b)

False

94.

Find parity bit for 1001011

a)

0

b)

1

c)

2

d)

None of the above

95.

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

a)

Degree

b)

Redundancy

c)

Generator

d)

None of the above

96.

The checksum of 0000 and 0000 is

a)

0101

b)

1010

c)

1111

d)

0000

97.

In ASCII, a single parity bit code can detect ________ errors.

a)

An odd number of

b)

Two

c)

No errors

d)

An even number of

98.

In networks where errors are infrequent, which approach is favored for efficiency?

a)

Hop-by-hop approach

b)

End-to-end approach

c)

Either one of the above

d)

Neither one of the above

99.

Which of the following statements is true about the stop-and-wait ARQ protocol?

a)

Stop-and-wait is only efficient if the link delay-bandwidth product is large

b)

Stop-and-wait is only efficient if the link delay-bandwidth product is small

c)

Stop-and-wait is only efficient if the link bandwidth is low

d)

Stop-and-wait is only efficient if the link bandwidth is high

100.

Consider a situation where an interactive application produces a packet to send each keystroke from the client and the server echoes each keystroke that it receives from the client. Which of following strategies for sending ACK frames in a Go-Back-N is appropriate for the situation?

a)

send an ACK frame immediately after each frame is received

b)

send an ACK frame after every other frame is received

c)

send an ACK frame when the next piggyback opportunity arises

d)

Any one of the above

101.

Consider a bulk data transfer application where a server sends a large file that is segmented in a number of full-size packets that are to be transferred to the client. Assume the channel has a low probability of error. Which of following strategies for sending ACK frames in a Go-Back-N is appropriate for the situation?

a)

send an ACK frame when the next piggyback opportunity arises

b)

send an ACK frame immediately after each frame is received

c)

send an ACK frame after every other frame is received

d)

Any one of the above

102.

Consider Selective Repeat ARQ flow control protocol. In the following scenario, what should be the value of frame number x at receiver B?

a)

2

b)

3

c)

4

d)

none

103.

A service model specifies a level of performance that can be expected in the transfer of information.

a)

True

b)

False

104.

A service offered at a given layer can include which of the following feature(s)

a)

Sequencing

b)

Reliability

c)

Timing

d)

All of the above

105.

Digital communication technologies may introduce errors in communication, which of the following can be used to provide reliable communication (2 answers)

a)

TCP

b)

DNS

c)

UDP

d)

HDLC

106.

Ensuring that information is not altered during transfer is associated with

a)

Authentication

b)

Confidentiality

c)

Integrity

d)

Availability

107.

Given 3 bits for sequence numbers, what is the maximum sliding window size at the receiver in Go Back 3 ARQ?

a)

3

b)

7

c)

8

d)

None of the above

108.

Given 3 bits for sequence numbers in Selective Repeat ARQ. If the sender already set the sliding window size to be 4, what is the maximum sliding window size at the receiver?

a)

3

b)

7

c)

8

d)

None of the above

109.

In the scenario above, what should be the value of frame number y at receiver B?

a)

3

b)

8

c)

7

d)

None of the above

110.

If the probability of error is very low in a communication link, which of the following statements is true about performance of ARQ protocol?

a)

Stop-and-wait and Go-back-N ARQ protocols have similar performance

b)

Stop-and-wait and Selective Repeat ARQ protocols have similar performance

c)

Go-back-N ARQ and Selective Repeat ARQ protocols have similar performance

d)

None of the above

111.

In peer-to-peer protocol, the purpose of Automatic Repeat Request is (2 answers)

a)

to ensure a sequence of information packet is delivered with an ACK request

b)

to ensure a sequence of information packet is delivered in order

c)

to ensure a sequence of information packet is delivered without errors or duplication despite transmission errors and losses

d)

to ensure a sequence of information packet is delivered out-of-order

112.

Which of the basic elements of ARQ is associated with negative acknowledgement

a)

Timeout mechanism

b)

ACKs

c)

NAKs

d)

Error detecting code

113.

In Go-Back-N ARQ, a procedure where transmission of a new frame is begun before the completion of time of the previous frame transmission is called

a)

Transitioning

b)

Pipelining

c)

Channeling

d)

None of the above

114.

In Stop-and-Wait protocol, sequence number are not required

a)

True

b)

False

115.

The disadvantage of Stop-and-Wait protocol

a)

Error free communication channel does not exist

b)

Acknowledgement may get lost

c)

Deadlock situation may occur

d)

All of the above

116.

Which of the following statements are true for the best-effort service of IP?

a)

Packets can arrive with errors or be lost

b)

Packets can arrive out-of-order

c)

Packets can arrive after very long delays

d)

All of the above

117.

Which of following services belong to the data link layer?

a)

Insert framing information into the transmitted stream to indicate the boundaries that define frames

b)

Provide error control to ensure reliable transmission

c)

Provide flow control to prevent the transmitter from overrunning the receiver buffer

d)

All of the above

118.

Which ARQ flow control protocol is used by TCP?

a)

Stop-and-Wait

b)

Selective Repeat

c)

Go-back-N

d)

None of the above

119.

By framing, frame boundaries can be determined using

a)

Character Counts

b)

Control Characters

c)

Flags

d)

All of the above

120.

Which of following statements are true about framing protocols?

a)

PPP uses character-based framing which requires byte stuffing

b)

HDLC uses Flag-based framing which required bit stuffing

c)

All of the above

d)

None of the above

121.

In IP network, which of the following statement is incorrect

a)

Packets can arrive out-of-order

b)

Packets can arrive with errors or be lost

c)

Packets can arrive after long delays

d)

Packets always arrive on time

122.

Framing involves identifying the beginning and end of a block of information within a digital stream

a)

True

b)

False

123.

Which of the following statements are true for PPP byte stuffing

a)

Malicious users may inflate bandwidth

b)

Size of frame varies unpredictably due to byte insertion

c)

All of the above

d)

None of the above

124.

In PPP authentication, which of the following is true for Password Authentication Protocol (3 answers)

a)

After several attempts, LCP closes link

b)

Initiator and authenticator share a secret key

c)

Transmitted unencrypted, susceptible to eavesdropping

d)

Initiator must send ID and password

125.

In HDLC frame format, flag is used to identify secondary station (1 or more octets)

a)

True

b)

False

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