MCQOPTIONS
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MCQOPTIONS
This section includes 105 Mcqs, each offering curated multiple-choice questions to sharpen your Computer Network knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
A 3000 Hz bandwidth noisy channel transmits bits with a signal to thermal noise ratio of 30 dB. What is the maximum data rate of the channel ? |
| A. | 30 kbps |
| B. | 00 kbps |
| C. | 60 kbps |
| D. | none of these |
| Answer» B. 00 kbps | |
| 52. |
Manchester code is a |
| A. | non-return to zero code |
| B. | polar code |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» D. none of these | |
| 53. |
Adaptive or dynamic directory used in packet routing changes |
| A. | within each user session |
| B. | with each user session |
| C. | at system generation time only |
| D. | none of these |
| Answer» B. with each user session | |
| 54. |
Non-polling system is |
| A. | TDMA |
| B. | stop and wait |
| C. | continuous ARQ |
| D. | none of these |
| Answer» B. stop and wait | |
| 55. |
Maximum data rate of a channel of 3000 Hz bandwidth and SNR of 30 dB is |
| A. | 75,000 bps |
| B. | 60,000 bps |
| C. | 30,000 bps |
| D. | 3,000 bps |
| Answer» D. 3,000 bps | |
| 56. |
PURE ALOHA |
| A. | Does not require global time synchronization |
| B. | does require global time synchronization |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» B. does require global time synchronization | |
| 57. |
In which ARQ, when a NAK is received, all frame sent since the last frame acknowledged an retransmitted |
| A. | stop-and-wait |
| B. | go-back-n |
| C. | selective-reject |
| D. | both (a) and (b) |
| Answer» C. selective-reject | |
| 58. |
What signal-to-noise ratio is needed to put a T1 carrier on a T0-kHz line ? |
| A. | 63 db |
| B. | 73 db |
| C. | 83 db |
| D. | 93 db |
| Answer» E. | |
| 59. |
If data rate of ring is 20 Mbps, signal propagation speed is 200 b/ms, then number of bits that can be placed on the channel of 200 km is |
| A. | 2000 bits |
| B. | 20,000 bits |
| C. | 1,000 bits |
| D. | none of these |
| Answer» C. 1,000 bits | |
| 60. |
Minimum number of bits required to represent all the symbols together is |
| A. | 15 |
| B. | 14 |
| C. | 12 |
| D. | 11 |
| Answer» B. 14 | |
| 61. |
A field in the Ethernet message packet is |
| A. | Type |
| B. | data |
| C. | address |
| D. | none of these |
| Answer» E. | |
| 62. |
Number of cross point needed for 10 lines in a cross point switch which is full duplex in nature and there are no self-connection is |
| A. | 100 |
| B. | 45 |
| C. | 8 |
| D. | 28 |
| Answer» C. 8 | |
| 63. |
Which of the following measures the number of lost or garbled messages as a fraction of the total sent in the sampling period ? |
| A. | Residual error rate |
| B. | Transfer failure probability |
| C. | Connection release failure probab |
| D. | Connection establishment failure probability |
| Answer» B. Transfer failure probability | |
| 64. |
Maximum data rate of a channel for a noiseless 3-kHz binary channel is |
| A. | 3000 bps |
| B. | 1500 bps |
| C. | 6000 bps |
| D. | none of these |
| Answer» D. none of these | |
| 65. |
The systems that can be used in both priority and non-priority modes is |
| A. | TDM |
| B. | Register insertion |
| C. | Carrier sense systems |
| D. | all of these |
| Answer» D. all of these | |
| 66. |
Data link layer retransmits the damaged frames in most networks. If probability of a frame's being damaged is p, then what is the mean number of transmissions required to send a frame if acknowledgements are never lost ? |
| A. | K / K - P |
| B. | 1 / K - P |
| C. | K / K(1 + p) |
| D. | p / K + 1 |
| Answer» C. K / K(1 + p) | |
| 67. |
Which of the following gates is described by the expression ? |
| A. | OR |
| B. | AND |
| C. | NOR |
| D. | NAND |
| Answer» E. | |
| 68. |
If a designer wants to design a point-to-point subnetwork with 10 routers of full duplex line, then total number of lines among them would be |
| A. | 10 |
| B. | 20 |
| C. | 45 |
| D. | 90 |
| Answer» E. | |
| 69. |
Which of the following is a time - division switch? |
| A. | TSI |
| B. | TDM bus |
| C. | crosspoint |
| D. | both (a) and (b) |
| Answer» E. | |
| 70. |
A terminal multiplexer has six 1200 bps terminals and (rf 300 bps terminals connected to it. The outgoing line is 9600 bps. What is the maximum value of n? |
| A. | 4 |
| B. | 16 |
| C. | 8 |
| D. | 28 |
| Answer» D. 28 | |
| 71. |
In which routing method do all the routers have a common database ? |
| A. | Distance vector |
| B. | Link state |
| C. | Link vector |
| D. | None of these |
| Answer» C. Link vector | |
| 72. |
In a crossbar with 1000 crosspoints, how many statistically are in use at any time ? |
| A. | 100 |
| B. | 250 |
| C. | 500 |
| D. | 1000 |
| Answer» C. 500 | |
| 73. |
Which of the following decides the role (sender or receiver) of a device on a network ? |
| A. | Line connection |
| B. | Link connection |
| C. | Line discipline |
| D. | Link decision |
| Answer» D. Link decision | |
| 74. |
The collision domain of tranditional Ethernet and Fast Ethernet respectively are |
| A. | 250m, 250m |
| B. | 250m, 2500m |
| C. | 2500m, 250m |
| D. | 2500m, 2500m |
| Answer» D. 2500m, 2500m | |
| 75. |
The secondary device in a multipoint configuration sends data in response to which of the following event ? |
| A. | ACK |
| B. | ENQ |
| C. | Poll |
| D. | Sel |
| Answer» D. Sel | |
| 76. |
For stop-and-wait flow control, for n data packets sent, how many acknowledgments are needed ? |
| A. | n |
| B. | n-1 |
| C. | 2n |
| D. | n + 1 |
| Answer» B. n-1 | |
| 77. |
For a sliding window of size n-1 (n sequence numbers), there can be maximum of how many frames sent but unacknowledged ? |
| A. | n -1 |
| B. | N |
| C. | n +1 |
| Answer» C. n +1 | |
| 78. |
How many crosspoints are needed in a single-stage switch with 40 inputs and 50 outputs ? |
| A. | 40 |
| B. | 90 |
| C. | 50 |
| D. | 2000 |
| Answer» E. | |
| 79. |
Collision domain can be compared to which distance data travels between two stations ? |
| A. | Minimum |
| B. | Maximum |
| C. | Virtual |
| D. | Both (a) and (b) |
| Answer» C. Virtual | |
| 80. |
Select incorrect statement in error retransmission used in continuous ARQ method |
| A. | Go-back-N method requires more storage at the receiving site |
| B. | Selective repeat involves complex login than GO-back-N |
| C. | Go-back-N has better line utilization |
| D. | Selective repeat has better line utilization |
| Answer» D. Selective repeat has better line utilization | |
| 81. |
Poll/select line discipline requires what to identify the packet recipient ? |
| A. | Timer |
| B. | Buffer |
| C. | Address |
| D. | Dedicated line |
| Answer» D. Dedicated line | |
| 82. |
Television channels are 6 MHz. How many bits can be sent if four level digital signals are used (assume a noiseless channel)? |
| A. | 24 Mbps |
| B. | 12 Mbps |
| C. | 6 Mbps |
| D. | 36 Mbps |
| Answer» B. 12 Mbps | |
| 83. |
In sliding window flow control, if window size is 63, what is the range of sequence numbers ? |
| A. | 0 to 63 |
| B. | 0 to 64 |
| C. | 1 to 63 |
| D. | 1 to 64 |
| Answer» B. 0 to 64 | |
| 84. |
What is the maximum burst length on an 155.52 Mbps ATM ABR connection whose PCR value 200,000 and whose L value is 25 msec ? |
| A. | 9 cells |
| B. | 12 cells |
| C. | 15 cells |
| D. | 18 cells |
| Answer» C. 15 cells | |
| 85. |
Phase shift keying (PSK.) method is used to modulate digital signals at 9600 bps using 16 levels. The line signals speed (i.e. modulation rate) will be |
| A. | 2400 bands |
| B. | 1200 bands |
| C. | 4800 bands |
| D. | 9600 bands |
| Answer» B. 1200 bands | |
| 86. |
Maximum data rate of a noiseless 4 kHz channel using T1 PCM system is |
| A. | 32 kbps |
| B. | 56 kbps |
| C. | 80 kbps |
| D. | 24 kbps |
| Answer» C. 80 kbps | |
| 87. |
In time division switches, if each memory access takes 100 ns and one frame period is 125ms, then maximum number of lines that can be supported is |
| A. | 625 |
| B. | 1250 |
| C. | 2300 |
| D. | 318 |
| Answer» B. 1250 | |
| 88. |
Given an infinite amount of buffer space. In the text it was stated that a satellite with two uplink and one downlink slotted ALOHA channels can achieve a downlink utilization of |
| A. | 0.536 |
| B. | 0.636 |
| C. | 0.736 |
| D. | 0.936 |
| Answer» D. 0.936 | |
| 89. |
A noiseless 3 kHz channel transmits bits with binary level signals. What is the maximum data rate ? |
| A. | 3 kbps |
| B. | 6 kbps |
| C. | 12 kbps |
| D. | 24 kbps |
| Answer» C. 12 kbps | |
| 90. |
What is the percentage of over head on a T1 carrier (1.544 Mbps) ? |
| A. | 25% |
| B. | 13% |
| C. | 20% |
| D. | 47% |
| Answer» C. 20% | |
| 91. |
A circuit switching network has the following characteristics : Set up time = 5 sec Propagation = 5 sec Message size = 1 M bits Data transmission rate = 1 M bits Data transmission rate = 1 Kbps Number of hops = 10 When will the last bit of the message reach the receiver ? |
| A. | t = 520 sec |
| B. | t = 1000 ms |
| C. | t = 250 sec |
| D. | t = 1025 sec |
| Answer» E. | |
| 92. |
A packet switching network (highly loaded) has the following characteristics: Propagation delay = 2 sec/hp. Data transmission rate = 1. Packet size = r bit = 512 bits. Number of of hops = 10. At what time the last bit of the last packet will reach the receiver ? |
| A. | 1024.5 sec |
| B. | 1038 sec |
| C. | 2048 sec |
| D. | 512 sec |
| Answer» B. 1038 sec | |
| 93. |
Two networks each provide reliable connection-oriented service. One of them offers a reliable byte stream and the other offers a reliable message stream. A process writes 1024 bytes, then |
| A. | both networks will receive 2048 bytes as a single unit |
| B. | message stream network will receive 1024 bytes only at one time. But byte stream network will receive 2048 bytes as a single unit. |
| C. | message stream network receives 2048 bytes as a whole. But bytes stream 1024 bytes only at a time. |
| D. | both will receive 1024 bytes at one time since there is a gap between writes |
| Answer» C. message stream network receives 2048 bytes as a whole. But bytes stream 1024 bytes only at a time. | |
| 94. |
A group of 2m - 1 routers are interconnected in a centralized binary tree. With router at each tree node. Router I communicates with router J by sending a message to the root of the tree. If root then sends the message back down J, the mean path length will be |
| A. | 2 (m - 2) |
| B. | 2 (2m - 1) |
| C. | m - 1 |
| D. | (2m - 1)/mJ |
| Answer» B. 2 (2m - 1) | |
| 95. |
In a time - division switch, which governs the destination of a packet stored in RAM? |
| A. | TDM bus |
| B. | Crosspoint |
| C. | crossbar |
| D. | Control unit |
| Answer» E. | |
| 96. |
The number of cross-points needed for 10 lines in a cross-point switch which is full duplex in nature and there are no self connection, is |
| A. | 100 |
| B. | 45 |
| C. | 50 |
| D. | 90 |
| Answer» C. 50 | |
| 97. |
Decryption and encryption of data are responsibility of |
| A. | physical layer |
| B. | data link layer |
| C. | presentation layer |
| D. | session layer |
| Answer» D. session layer | |
| 98. |
Protection of data from a natural disaster such as a tornado belongs to which of the following network issue ? |
| A. | Performance |
| B. | Reliability |
| C. | Security |
| D. | Management |
| Answer» C. Security | |
| 99. |
A bridge has access to which address of a station on the same network ? |
| A. | Physical |
| B. | Network |
| C. | Service access point |
| D. | All of these |
| Answer» B. Network | |
| 100. |
A high speed communication equipment typically would not be needed for |
| A. | |
| B. | transferring large volume of data |
| C. | supporting communication between nodes in a LAN |
| D. | all of these |
| Answer» B. transferring large volume of data | |