NTA UGC NET Computer Science Paper II Solved July 2018 - Part 3

41.       A slotted ALOHA network transmits 200-bit frames using a shared channel with a 200 Kbps bandwidth. Find the throughput of the system, if the system (all stations put together) produces 250 frames per second:
(1) 49
(2) 368
(3) 149
(4) 151
Answer: 1
42.       The period of a signal is 100 ms. Its frequency is .............
(1) 1003 Hertz
(2) 10−2 KHz
(3) 10−3 KHz
(4) 105 Hertz
Answer: 2
43.       The dotted-decimal notation of the following IPV4 address in binary notation is ...................
10000001 00001011 00001011 11101111
Answer: 3
44.       Which of the following statements are true?
(a) Advanced Mobile Phone System (AMPS) is a second generation cellular phone system.
(b) IS - 95 is a second generation cellular phone system based on CDMA and DSSS.
(c) The Third generation cellular phone system will provide universal personnel communication.
(1) (a) and (b) only
(2) (b) and (c) only
(3) (a), (b) and (c)
(4) (a) and (c) only
Answer: 2
45.       Match the following symmetric block ciphers with corresponding block and key sizes:
List - I
(a) DES
(b) IDEA
(d) AES
List - II
(i) block size 64 and key size ranges between 32 and 448
(ii) block size 64 and key size 64
(iii) block size 128 and key sizes 128, 192, 256
(iv) block size 64 and key size 128
      (a)  (b)  (c)   (d)
(1) (iv)  (ii)   (i)   (iii)
(2) (ii)   (iv)  (i)   (iii)
(3) (ii)   (iv)  (iii)  (i)
(4) (iv)  (ii)   (iii)  (i)
Answer: 2
46.       Which of the following statements are true?
(a) Three broad categories of Networks are
(i) Circuit Switched Networks
(ii) Packet Switched Networks
(iii) Message Switched Networks
(b) Circuit Switched Network resources need not be reserved during the set up phase.
(c) In packet switching there is no resource allocation for packets.
(1) (a) and (b) only
(2) (b) and (c) only
(3) (a) and (c) only
(4) (a), (b) and (c)
Answer: 3
47.       In Challenge-Response authentication the claimant ...............
(1) Proves that she knows the secret without revealing it
(2) Proves that she doesn’t know the secret
(3) Reveals the secret
(4) Gives a challenge
Answer: 1
48.       Decrypt the message “WTAAD” using the Caesar Cipher with key=15.
Answer: 2
49.       To guarantee correction of upto t errors, the minimum Hamming distance dmin in a block code must be ................
(1) t+1
(2) t−2
(3) 2t−1
(4) 2t+1
Answer: 4
50.    Encrypt the Message “HELLO MY DEARZ” using Transposition Cipher with
Answer: 3
51.    At a particular time of computation, the value of a counting semaphore is 10. Then 12 P operations and “x” V operations were performed on this semaphore. If the final value of semaphore is 7, x will be:
(1) 8
(2) 9
(3) 10
(4) 11
Answer: 2
52.    In a paged memory, the page hit ratio is 0.40. The time required to access a page in secondary memory is equal to 120 ns. The time required to access a page in primary memory is 15 ns. The average time required to access a page is ..................
(1) 105
(2) 68
(3) 75
(4) 78
Answer: 4
53.    In a multi-user operating system, 30 requests are made to use a particular resource per hour, on an average. The probability that no requests are made in 40 minutes, when arrival pattern is a poisson distribution, is ...............
(1) e−15
(2) 1−e−15
(3) 1−e−20
(4) e−20
Answer: 4
54.    Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O?
(1) I/O protection is ensured by operating system routines.
(2) I/O protection is ensured by a hardware trap.
(3) I/O protection is ensured during system configuration.
(4) I/O protection is not possible.
Answer: 1
55.    Which UNIX/Linux command is used to make all files and sub-directories in the directory “progs” executable by all users?
(1) chmod −R a+x progs
(2) chmod −R 222 progs
(3) chmod −X a+x progs
(4) chmod −X 222 progs
Answer: 1
56.    Which of the following statements are true?
(a) External Fragmentation exists when there is enough total memory space to satisfy a request but the available space is contiguous.
(b) Memory Fragmentation can be internal as well as external.
(c) One solution to external Fragmentation is compaction.
(1) (a) and (b) only
(2) (a) and (c) only
(3) (b) and (c) only
(4) (a), (b) and (c)
Answer: 3
57.    Page information in memory is also called as Page Table. The essential contents in each entry of a page table is/are ....................
(1) Page Access information
(2) Virtual Page number
(3) Page Frame number
(4) Both virtual page number and Page Frame Number
Answer: 3
58.    Consider a virtual page reference string 1, 2, 3, 2, 4, 2, 5, 2, 3, 4. Suppose LRU page replacement algorithm is implemented with 3 page frames in main memory. Then the number of page faults are .................
(1) 5
(2) 7
(3) 9
(4) 10
Answer: 2
59.    Consider the following three processes with the arrival time and CPU burst time given in milliseconds:
The Gantt Chart for preemptive SJF scheduling algorithm is ...............
Answer: 2
60.    In which of the following scheduling criteria, context switching will never take place?
(2) Preemptive SJF
(3) Non-preemptive SJF
(4) Preemptive priority
Answer: 3

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