101. Link encryption

is more secure than end-to-end encryption

is less secure than end-to-end encryption

cannot be used in a large network

is used only to detect errors

102. Seeks analysis

is used for analyzing paging problems

is used for analyzing device busy problems

is used for analyzing control-unit busy problems

is only shown on real-time displays

103. Trojan-Horse programs

are legitimate programs that allow unauthorized access

are hacker programs that do not show up on the system

really do not usually work

usually are immediately discovered

104. Pre-emptive scheduling is the strategy of temporarily suspending a running process

before the CPU time slice expires

to allow starving processes to run

when it requests I/O

none of these

105. In Round Robin CPU scheduling, as the time quantum is increased, the average turn around time

increases

decreases

remains constant

varies irregularly

106. Which of the following refers to the associative memory?

Address of the data is generated by the CPU

Address of the data is supplied by the users.

There is no need for an address ie the data is used as an address

Data are accessed sequentially

107. Consider a logical address space of 8 pages of 1024 words mapped into memory of 32 frames. How many bits are there in the physical address?

9 bits

11 bits

13 bits

15 bits

108. Consider a logical address space of 8 pages of 1024 words mapped into memory of 32 frames. How many bits are there in the logical address?

9 bits

11 bits

13 bits

15 bits

109. Consider a computer with 8 Mbytes of main memory and a 128 K cache. The cache block size is 4 K. It uses a direct mapping scheme for cache management. How many different main memory blocks can map onto a given physical cache block ?

2048

256

64

None of these

110. The first-fit, best-fit and the worst-fit algorithm can be used for

contiguous allocation of memory

linked allocation of memory

indexed allocation of memory

all of these

111. If there are 32 segments, each of size 1 K byte, then the logical address should have

13 bits

14 bits

15 bits

16 bit

112. Dirty bit is used to show the

page with corrupted data

the wrong page in the memory

page that is modified after being loaded into cache memory

page that is less frequently accessed

113. In real-time operating systems, which of the following is the most suitable scheduling scheme?

round-robin

first-come-first-served

preemptive

random scheduling

114. In a paged memory, the page hit ratio is 0.35. The time required to access a page in secondary memory is equal to 100 ns. The time required to access a page in primary memory is 10 ns. The average time required to access a page is

3.0 ns

68.0 ns

68.5 ns

78.5 ns

115. Working set (t, k) at an instant of time, t, is

the set of k future references that the operating system will make

the set of future references that the operating system will make in the next 'k' time units

the set of k reference with high frequency

the set of pages that have been referenced in the last k time units

116. Distributed systems should

meet prescribed time constraints

aim better resource sharing

aim better system utilization

aim low system overhead

117. Fence register is used for

CPU protection

memory protection

file protection

all of these

118. Determine the number of page faults when references to pages occur in the following order : 1, 2, 4, 5, 2, 1, 2, 4. Assume that the main memory can accommodate 3 pages and the main memory already has the pages 1 and 2, with page 1 having been brought earlier than page 2. (LRU algorithm is used)

3

5

4

None of these

119. A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits The transfer rate will be

2.5 Mbits/s

4.25 Mbits/s

1.5Mbits/s

3.75Mbits/s

120. A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits The average latency time (assume the head can move from one track to another only by traversing the entire track) is

2.5 s

2.9 s

3.1 s

3.6 s