51. Which transmission technique guarantees that data packets will be received by the receiver in the same order in which they were sent by the sender?
a. Broadcasting
b. Unicasting
c. Packet switching
d. Circuit switching
Answer: (d).Circuit switching

52. Which of the following control fields in TCP header is used to specify whether the sender has no more data to transmit?
a. FIN
b. RST
c. SYN
d. PSH
Answer: (a).FIN

53. Which are the two modes of IP security?
a. Transport and certificate
b. Transport and tunnel
c. Certificate and tunnel
d. Preshared and transport
Answer: (b).Transport and tunnel

54. A message "COMPUTERNETWORK" encrypted (ignore quotes) using columnar transposition cipher with a key "LAYER". The encrypted message is :

55. Suppose a digitized voice channel is made by digitizing 8 kHz bandwidth analog voice signal. It is required to sample the signal at twice the highest frequency (two samples per hertz). What is the bit rate required, if it is assumed that each sample requires 8 bits?
a. 32 kbps
b. 64 kbps
c. 128 kbps
d. 256 kbps
Answer: (c).128 kbps

56. The maximum payload of a TCP segment is :
a. 65,535
b. 65,515
c. 65,495
d. 65,475
Answer: (c).65,495

57. In a binary Hamming Code the number of check digits is r then number of message digits is equal to :
a. 2^r – 1
b. 2^r – r – 1
c. 2^r – r + 1
d. 2^r + r – 1
Answer: (b).2^r – r – 1

58. In a digital transmission, the receiver clock is 0.1 percent faster than the sender clock. How many extra bits per second does the receiver receive if the data rate is 1 Mbps?
a. 10 bps
b. 100 bps
c. 1000 bps
d. 10000 bps
Answer: (c).1000 bps

59. Match the following cryptographic algorithms with their design issues:
List-I                                        List-II

a. DES                              i.  Message Digest

b. AES                              ii.  Public Key

c. RSA                              iii. 56-bit key

d. SHA-1                          iv. 128-bit key

a       b       c       d
a. ii       i       iv       iii
b. iii       i       iv       ii
c. iii       iv       ii       i
d. iv       i       ii       iii
Answer: (c).iii       iv       ii       i

60. Ten signals, each requiring 3000 Hz, are multiplexed on to a single channel using FDM. How much minimum bandwidth is required for the multiplexed channel ? Assume that the guard bands are 300 Hz wide.
a. 30,000
b. 32,700
c. 33,000
d. None of the above
Answer: (b).32,700

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