81. Viruses

another form of computer attack is virus

virus are designed to spread into other programs and can wreak havoc in a system

it modifying or destroying files and causing system crashes and program malfunctions

all of these

82. The most common approach to authenticating a user identity is

user passwords

user log in

hardware device

none of these

83. Boot strap or vector is called

grappling hook program

main program

secondary program

primary storage

84. A major security problem for operating system is

authentication problem

physical problem

human problem

none of these

85. Real-time displays

are used only for capacity planning

are most useful for showing performance problems

are useless for capacity planning

cannot show the system paging rate

86. Global locks

synchronize access to local resources

synchronize access to global resources

are used to avoid local locks

prevent access to global resources

87. Control-unit busy

is the same as device busy

shows the availability of the path of devices

can be prevented with more devices

can be prevented by reducing the paging rate

88. A long-term process display should

show which processes used the most processor time

show process activity by time interval

show resources used by the most active processes

all of these

89. Device busy

is good, since that means the device is in use

is bad, since that means the device is not available

is bad only if the device busy rate is too high

depends upon the system paging rate

90. A long-term monitor

should show any immediate performance problems

should show I/O, paging, and processor activity

need show only the I/O and processor activity

usually reports only on terminal displays

91. 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

92. 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

93. 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

94. 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

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

increases

decreases

remains constant

varies irregularly

96. 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

97. 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

98. 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

99. 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

100. 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