Unit 2- computer network mcq questions

Hey Guys, If you are preparing Computer Network for the AKTU exams, then These are the Important computer network mcq questions. so must go through these questions.

Note*: Do not depend only on these MCQ’s, Yes surely these questions help you in AKTU exams so do it first and after that if you have enough time, study all the core topics as well.

You can also check out these subjects as well: Data Compression, Machine learning, Image processing

Unit 2: Computer network MCQ questions


1. The two sublayers of a Data Link layer are

  1. LLC Logical Link Control Layer
  2. MAC Medium Access Control Layer
  3. Both A and B
  4. Data Layer
    Answer: Option(c)

2. Which is the protocol that maps varying IP addresses to the Physical MAC Address of a machine in a LAN network?

  1. ARQ (Automatic Repeat Request)
  2. ARP (Address Resolution Protocol)
  3. SLIP (Serial Line Internet Protocol)
  4. PLIP (Parallel Line Internet Protocol)
    Answer: Option(b)

3. The types of data services offered by an LLC (Logical Link Control) layer are

  1. Connectionless which is fast and unreliable
  2. Connection Oriented which is slow and reliable
  3. Both A and B
  4. None
    Answer: Option(c)

4. Choose the Protocols working in the Data Link Control Layer of OSI model below

  1.  ATM (Asynchronous Transfer Mode), Frame Relay
  2. HDLC (High Level Data Link Control), SDLC (Synchronous Data Link Control)
  3. ARP (Address Resolution Protocol), IEEE802.3
  4. All the above
    Answer: Option(d)

5. The functions of a Logical Link Layer (LLC) are

  1. Error control
  2. Flow control
  3. Creating and managing the communication link between two devices with the help of the Transport layer.
  4. All the above
    Answer: Option(d)

6. Automatic repeat request error management mechanism is provided by ________

  1. logical link control sublayer
  2. media access control sublayer
  3. network interface control sublayer
  4. application access control sublayer
    Answer: Option(a)

Automatic repeat request error management mechanism is provided by ________

  1. logical link control sublayer
  2. media access control sublayer
  3. network interface control sublayer
  4. application access control sublayer
    Answer: Option(a)

7. The Dialup connections to access the internet uses ___ protocol.

  1. PPP (Point to Point protocol)
  2. X.25 protocol
  3. PLIP protocol
  4. None
    Answer: Option(a)

8. Which protocols adopted the standards of HDLC (High Level Link Control) protocol?

  1. X.25 protocol as LAPB (Link Access Procedure Balanced, V.42 protocol as LAPM (Link Access Procedure for Modems)
  2. Frame Relay protocol as LAPF (Link Access Procedure for Frame Relay)
  3. ISDN (Integrated Services Digital Network) protocol as LAPD (Link Access Procedure on D channel)
  4. All the above
    Answer: Option(d)

9. Header of a frame generally contains

  1. synchronization bytes
  2. addresses
  3. frame identifier
  4. all of the mentioned
    Answer: Option(d)

10. Which sublayer of the data link layer
performs data link functions that depend upon
the type of medium?
a. logical link control sublayer
b. media access control sublayer
c. network interface control sublayer
d. error control sublayer
Answer: Option(b)
11. CRC stands for __________
a. cyclic redundancy check
b. code repeat check
c. code redundancy check
d. cyclic repeat check
Answer: Option(a)
12. When 2 or more bits in a data unit has been changed during the transmission, the error is called _____
a. random error
b. burst error
c. inverted error
d. double error
Answer: Option(b)
13. Which of the following is a data link protocol?
a. ethernet
b. point to point protocol
c. hdlc
d. all of the mentioned
Answer: Option(d)
14. Which of the following is the multiple access protocol for channel access control?
a. CSMA/CD
b. CSMA/CA
c. Both CSMA/CD & CSMA/CA
d. HDLC
Answer: Option(c)
15. The technique of temporarily delaying
outgoing acknowledgements so that they can
be hooked onto the next outgoing data frame is
called ____________
a. piggybacking
b. cyclic redundancy check
c. fletcher’s checksum
d. parity check
Answer: Option(a)
16. Which of the following uses a very thin
glass or plastic fiber through which pulses of
light travel?
a. Cat 1
b. Optical fiber
c. Twisted pair
d. Coax
Answer: Option(b)
17. When does the station B send a positive
acknowledgement (ACK) to station A in Stop
and Wait protocol?
a. only when no error occurs at the
transmission level
b. when retransmission of old packet in a
novel frame is necessary
c. only when station B receives frame
with errors
d. all of the above
Answer: Option(a)
18. Which consequences are more likely to
occur during the frame transmission in
StopandWait ARQ mechanism?
a. Loss of frame or an acknowledgementCOMPUTER NETWORKS 2020-21
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b. Delay in an acknowledgement
c. Normal operation
d. All of the above
Answer: Option(d)
19. Which provision can resolve / overcome
the shortcomings associated with duplication
or failure condition of Stop and Wait
Automatic Repeat Request protocol especially
due to loss of data frames or non reception of
acknowledgement?
a. Provision of sequence number in the
header of message
b. Provision of checksum computation
c. Both a & b
d. None of the above
Answer: Option(a)
20. Which ARQ mechanism deals with the
transmission of only damaged or lost frames
despite the other multiple frames by increasing
the efficiency & its utility in noisy channels?
a. GoBackN ARQ
b. Selective Repeat ARQ
c. StopandWait ARQ
d. All of the above
Answer: Option(b)
21. Which feature of Go Back N ARQ
mechanism possesses an ability to assign the
sliding window in the forward direction?
a. Control Variables
b. Sender Sliding Window
c. Receiver Sliding Window
d. Resending of frames
Answer: Option(b)
22. Which operational mode/s of HDLC
support/s the balanced configuration by
governing point to point link connectivity in
addition to the primary as well as secondary
functions performed by the station?
a. NRM
b. ABM
c. Both a & b
d. None of the above
Answer: Option(b)
23. Which category of HDLC frames
undergoes error and flow control mechanisms
by comprising send and receive sequence
numbers?
a. Uframes
b. Iframes
c. Sframes
d. All of the above
Answer: Option(c)
24. Which type of Sframe in HDLC exhibit the
correspondence of last three bits [N(R)] by
defining the negative acknowledgement
(NAK) number with the code value of ’01’?
a. Receive ready
b. Receive not ready
c. Reject
d. Selective Reject
Answer: Option(c)
25. Which among the following represents the
objectives/requirements of Data Link Layer?
a. Frame Synchronization
b. Error & Flow Control
c. Both a & b
d. None of the above
Answer: Option(c)
26. When does the station B send a positive
acknowledgement (ACK) to station A in Stop
and Wait protocol?
a. only when no error occurs at the
transmission level
b. when retransmission of old packet in a
novel frame is necessary
c. only when station B receives frame
with errorsCOMPUTER NETWORKS 2020-21
11 University Academy
d. all of the above
Answer: Option(a)
27. For pure ALOHA, the maximum channel
utilization is
a. 100%
b. 50%
c. 36%
d. 18%
Answer: Option(d)
28. The program used to determine the round trip delay between a workstation and a destination address is
a. Tracert
b. Traceroute
c. Ping
d. Pop
Answer: Option(b)
29. What is the difference between the Ethernet frame preamble field and the IEEE 802.3 preamble and start of frame Delimiter fields?
a. 1 byte
b. 1 bit
c. 4 bit
d. 16 bit
Answer: Option(a)
30. Which of the following approaches to switching share networks resource?
a. Circuit switching
b. Packet switching
c. Both A and B
d. None of these
Answer: Option(b)
31. Determine the maximum length of the cable (in km) for transmitting data at a rate of 500 Mbps in an Ethernet LAN with frames of size 10,000 bits. Assume the signal speed in the cable to be 2,00,000 km/s.
a. 1
b. 2
c. 2.5
d. 5
Answer: Option(b)
32. Let G(x) be the generator polynomial used for CRC checking. What is the condition that should be satisfied by G(x) to detect odd number of bits in error?
a. G(x) contains more than two terms
b. G(x) does not divide 1+x^k, for any k not exceeding the frame length
c. 1+x is a factor of G(x)
d. G(x) has an odd number of terms
Answer: Option(c)
33. In Ethernet when Manchester encoding is used, the bit rate is:
a. Half the baud rate.
b. Twice the baud rate.
c. Same as the baud rate.
d. None of the above
Answer: Option(a)
34. In a token ring network the transmission speed is 10^7 bps and the propagation speed is 200 metres/micro second. The 1- bit delay in this network is equivalent to:
a. 500 metres of cable.
b. 200 metres of cable.
c. 20 metres of cable.
d. 50 metres of cable
Answer: Option(c)
35. The message 11001001 is to be transmitted using the CRC polynomial x^3 + 1 to protect it from errors. The message that should be transmitted is:
a. 11001001000
b. 11001001011
c. 11001010
d. 110010010011
Answer: Option(b)
36. The distance between two stations M and N is L kilometers. All frames are K bits long. The propagation delay per kilometer is t seconds. Let R bits/second be the channel  capacity. Assuming that processing delay is negligible, the minimum number of bits for
the sequence number field in a frame for maximum utilization, when the sliding window protocol used is:
a. A
b. B
c. C
d. D
Answer: Option(c)
37. A bit-stuffing based framing protocol uses an 8-bit delimiter pattern of 01111110. If the output bit-string after stuffing is 01111100101, then the input bit-string is
a. 0111110100
b. 0111110101
c. 0111111101
d. 0111111111
Answer: Option(b)
38. Station A uses 32 byte packets to transmit messages to Station B using a sliding window protocol. The round trip delay between A and B is 80 milliseconds and the bottleneck bandwidth on the path between A and B is 128 kbps. What is the optimal window size that A should use?
a. 20
b. 40
c. 160
d. 320
Answer: Option(b)
39. Suppose the round trip propagation delay for a 10 Mbps Ethernet having 48-bit jamming signal is 46.4 ms. The minimum frame size
is
a. 94
b. 416
c. 464
d. 512
Answer: Option(c)
40. How many 8-bit characters can be transmitted per second over a 9600 baud serial communication link using asynchronous mode of transmission with one start bit, eight data bits, two stop bits, and one parity bit ?
a. 600
b. 800
c. 876
d. 1200
Answer: Option(b)
41. Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (108 bits per second) over a 1 km (kilometre) cable with no repeaters. If the minimum frame size required for this network is 1250 bytes, what is the signal speed (km/sec) in the cable?
a. 8000
b. 10000
c. 16000
d. 20000
Answer: Option(d)
42. Which one of the following statements is
FALSE?
a. Packet switching leads to better utilization of bandwidth resources than circuit switching.
b. Packet switching results in less variation in delay than circuit switching.
c. Packet switching requires more per packet processing than circuit switching
d. Packet switching can lead to reordering unlike in circuit switching
Answer: Option(b)
43. Which of the following statements is TRUE about CSMA/CD
a. IEEE 802.11 wireless LAN runs CSMA/CD protocol
b. Ethernet is not based on CSMA/CD protocol
c. CSMA/CD is not suitable for a high propagation delay network like satellite network
d. There is no contention in a CSMA/CD network
Answer: Option(c)
44. A sender uses the Stop-and-Wait ARQ protocol for reliable transmission of frames. Frames are of size 1000 bytes and the transmission rate at the sender is 80 Kbps (1Kbps = 1000 bits/second). The size of an acknowledgment is 100 bytes and the transmission rate at the receiver is 8 Kbps. The one-way propagation delay is 100 milliseconds. Assuming no frame is lost, the sender throughput is __________
bytes/second.
a. 2500
b. 2000
c. 1500
d. 500
Answer: Option(a)
45. In an Ethernet local area network, which one of the following statements is TRUE ?
a. A station stops to sense the channel once it starts transmitting a frame.
b. The purpose of the jamming signal ito pad the frames that are smaller than the minimum frame size.
c. A station continues to transmit the packet even after the collision is detected.
d. The exponential backoff mechanism reduces the probability of collision on retransmissions
Answer: Option(d)
46. How many bytes of data can be sent in 15seconds over a serial link with baud rate of 9600 in asynchronous mode with odd parity and two stop bits in the frame?
a. 10,000 bytes
b. 12,000 bytes
c. 15,000 bytes
d. 27,000 bytes
Answer: Option(b)
47. The minimum frame size required for a CSMA/CD based computer network running at 1 Gbps on a 200m cable with a link speed of 2 × 108m/s is
a. 125 bytes
b. 250 bytes
c. 500 bytes
d. None of these
Answer: Option(b)
48. Suppose that the one-way propagation delay for a 100 Mbps Ethernet having 48-bit jamming signal is 1.04 micro-seconds. The minimum frame size in bits is:
a. 112
b. 160
c. 208
d. 256
Answer: Option(d)
49. Which of the following statement is False
about the efficiency of the given channel?
a. If we want to send big packets on the
channel, then Stop and Wait is good
choice.
b. If length of packet increases,
efficiency of channel also increases.
c. Distance between sender and
receiver is directly proportional to
efficiency of channel.
d. Efficient might be less if capacity of
channel is high
Answer: Option(c)
50. Consider a link with packet loss probability
of 0.2. What is the expected number of
transmissions it would take to transfer 200
packets given that the stop and wait protocol
is used?
a. 125
b. 250
c. 225COMPUTER NETWORKS 2020-21
14 University Academy
d. 150
Answer: Option(b)
51. Which of the following devices takes data
sent from one network device and forwards
it to the destination node based on MAC
address ?
a. Hub
b. Modem
c. Switch
d. Gateway
Answer: Option(c)
52. In Ethernet CSMA/CD, the special bit
sequence transmitted by media access
management to handle collision is called
a. Preamble
b. Postamble
c. Jam
d. None of the above
Answer: Option(c)
53. Let C be a binary linear code with minimum
distance 2t + 1 then it can correct upto _____
bits of error.
a. t + 1
b. t
c. t – 2
d. t / 2
Answer: Option(b)
54. In CRC if the data unit is 100111001 and the
divisor is 1011 then what is dividend at the
receiver?
a. 100111001101
b. 100111001011
c. 100111001
d. 100111001110
Answer: Option(b)
55. A certain population of ALOHA users
manages to generate 70 request/sec. If the
time is slotted in units of 50 msec, then
channel load would be
a. 4.25
b. 3.5
c. 350
d. 450
Answer: Option(b)
56. Match the following
a. (1)
b. (2)
c. (3)
d. (4)
Answer: Option(a)
57. If the frame to be transmitted is 1101011011
and the CRC polynomial to be used for
generating checksum is x
4+ x + 1, then what
is the transmitted frame?
a. 11010110111011
b. 11010110111101
c. 11010110111110
d. 11010110111001
Answer: Option(c)
58. What will be the efficiency of a Stop and
Wait protocol, if the transmission time for a
frame is 20ns and the propagation time is
30ns?
a. 20%
b. 25%
c. 40%
d. 66%
Answer: Option(b)
59. Bit stuffing refers to
a. inserting a 0 in user stream
to differentiate it with a flagCOMPUTER NETWORKS 2020-21
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b. inserting a 0 in flag stream to
avoid ambiguity
c. appending a nipple to the flag
sequence
d. appending a nipple to the use data stream
Answer: Option(a)
60. _______ can detect burst error of length less than or equal to degree of the polynomial and detects burst errors that affect odd number of bits.

  1. Hamming Code
  2. CRC
  3. VRC
  4. None of the above
    Answer: Option(b

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