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
(1)
111.56.45.239
(2)
129.11.10.238
(3)
129.11.11.239
(4)
111.56.11.239
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.
Code:
(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
(c) BLOW
FISH
(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
Code:
(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.
Code:
(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.
(1) LIPPS
(2) HELLO
(3) OLLEH
(4) DAATW
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
(1) HLLEO YM
AEDRZ
(2) EHOLL
ZYM RAED
(3) ELHL
MDOY AZER
(4) ELHL
DOMY ZAER
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.
Code:
(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:
Answer: 2
60. In
which of the following scheduling criteria, context switching will never take
place?
(1) ROUND
ROBIN
(2)
Preemptive SJF
(3)
Non-preemptive SJF
(4)
Preemptive priority
Answer: 3
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