21. Find the false statement:
a. In modern Cryptography, symmetric key algorithms use same key both for Encryption and Decryption
b. The symmetric cipher DES (Data Encryption Standard) was widely used in the industry for security product
c. The AES (Advanced Encryption Standard )   cryptosystem allows variable key lengths  of size 56 bits and 124 bits
d. Pubiic  key algorithms use two different keys for Encryption and Decryption
Answer: (c).The AES (Advanced Encryption Standard )   cryptosystem allows variable key lengths  of size 56 bits and 124 bits

22. The message 11001001 is to be transmitted  using the CRC  polynomial  x3 +1 to protect it from errors. The message that should  be transmitted is :
a. 110010011001
b. 11001001
c. 110010011001001
d. 11001001011
Answer: (d).11001001011

23. What is the bit rate for transmitting uncompressed 800 x 600 pixel colour frames with 8 bits/pixel at 40 frames/second?
a. 2.4 Mbps
b. 15.36 Mbps
c. 153.6 Mbps
d. 1536 Mbps
Answer: (c).153.6 Mbps

24. In IPV 4, the IP address belongs to
a. Class A
b. Class B
c. Class C
d. Class D
Answer: (c).Class C

25. Which layer of OSI reference model is responsible for decomposition of messages and generation of sequence numbers to 'ensure correct re-composition from end to end of the network?'
a. Physical
b. Data-link
c. Transport
d. Application
Answer: (c).Transport

26. A client-server system uses a satellite network, With the satellite at a height of 40,000 kms. What is the best-case delay in response to a request (Note that the speed of light in air is 3,00,000 km/second).
a. 133.33 m sec
b. 266.67 m sec
c. 400.00 m sec
d. 533.33 m sec
Answer: (b).266.67 m sec

27. The start and stop bits are used in serial communication for
a. error detection
b. error correction
c. synchronization
d. slowing down the communication
Answer: (c).synchronization

28. ___________ is a type of transmission  impairment in which the SIgnal looses strength due to The resistance of the transmission medium.
a. Attenuation
b. Distortion
c. Noise
d. Decible
Answer: (a).Attenuation

29. Match the following :

                List - I                                List - II

a. Call control protocol         i. Interface between Base Transceiver Station (BTS) and Base Station Controller (BSC)

b. A-bis                                  ii. Spread spectrum

c. BSMAP                                iii. Connection management

d. CDMA                                 iv. Works between Mobile Switching Centre (MSC) and Base Station Subsystem (BSS)

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

30. An analog signal has a bit rate of 6000 bps and a baud rate of 2000 baud. How many data elements are carried by each signal element?
a. 0.336 bits baud
b. 3 bits baud
c. 120,00,000 bits baud
d. None of the above
Answer: (b).3 bits baud

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