Operating System NTA UGC NET Question Analysis Part-1

Q1➡ | NET June 2023
Consider the following table of arrival time and burst time for three processes P0.P1 P2:
Consider the following table of arrival time and burst time for three processes P0.P1 P2:
Process	arrival time	Burst time
P0	0 ms	7
P1	1 ms	3
P2	2 ms	7




The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or completion of a process. What is the average waiting time for the three processes?

The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or completion of a process. What is the average waiting time for the three processes?
i ➥ 3 ms
ii ➥ 3.67 ms
iii ➥ 4.47 ms
iv ➥ 4 ms
Best Explanation:
Answer: (ii)
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Q2➡ | NET June 2023
Consider the following statements:
 S1: LRU page replacement algorithm suffers from the belady’s anomaly
 S2: Shortest remaining time first scheduling may cause starvations
 S3: Stack is shared by all threads in a process
i ➥ S1, S2 and S3 are true
ii ➥ S1, S3 false and S2 is true
iii ➥ S1, S2 are false and S3 is true
iv ➥ S1, S2 and S3 are false
Best Explanation:
Answer: (ii)
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Q3➡ | NET June 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: A process involves a library function to create a thread.
Reason R: The threads make system calls to convey their resource and I/O requirement to the Kernel.
In the light of the above statements, choose the correct answer from the options given below.
i ➥ Both A and R are true and R is the correct explanation of A
ii ➥ Both A and R are true but R is NOT the correct explanation of A
iii ➥ A is true but R is false
iv ➥ A is false but R is true
Best Explanation:
Answer: (ii)
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Q4➡ | NET June 2023
Given below are two statements:
Which of the following statement/s is/are correct with respect to virtual memory

Statement I: Address translation is performed for every logical address used during the execution of a program.
Statement II: A program can execute only when all of its components are loaded in the memory.

In the light of the above statements, choose the most appropriate answer from the options given below.
i ➥ Both Statement I and Statement II are correct
ii ➥ Both Statement I and Statement II are incorrect
iii ➥ Statement I is correct but Statement II is incorrect
iv ➥ Statement I is incorrect but Statement II is correct
Best Explanation:
Answer: (iii)
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Q5➡ | NET June 2023
At a particular time of computation, the value of a counting semaphore is 7. Then 20 p operations and ‘x’ V operations were completed on this semaphore. If the final value of semaphore is 5. x will be ?
i ➥ 15
ii ➥ 22
iii ➥ 18
iv ➥ 14
Best Explanation:
Answer: (iii)
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Q6➡ | NET June 2023

Match the pairs:
a) Critical region
b) Wait/signal
c) Working set
d) Deadlock	1) Hoare's monitor
2) Mutual exclusion
3) principle of locality
4) circular wait


 

Choose the correct answer from the options given below:

Choose the correct answer from the options given below:
i ➥ A-IV B-I  C-III  D-II
ii ➥ A-II  B-I  C-III D-IV
iii ➥ A-I B-II C-III D-IV
iv ➥ A-IV  B-III  C-I  D-II
Best Explanation:
Answer: (ii)
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Q7➡ | NET June 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
 A virtual memory system uses first-in first-out page replacement policy and allocates a fixed number of frames to a process
Assertion A: Increasing number of page frames allocated to a process sometimes increases the page fault rate.
Reason R: Some programs do not exhibit locality of reference.
 
In the light of the above statements, choose the correct answer from the options given below
i ➥ Both A and R are true and R is the correct explanation of A
ii ➥ Both A and R are true but R is NOT the correct explanation of A
iii ➥ A is true but R is false
iv ➥ A is false but R is true
Best Explanation:
Answer: (ii)
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Q1➡ | NET December 2022
In Linux Operating system, when ___________ is invoked , it is passed a set of flags that determine how much sharing is to take place between the parent and child tasks.
i ➥ Fork()
ii ➥ Clone()
iii ➥ Pthread()
iv ➥ Thread()
Best Explanation:
Answer: (ii)
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Q2➡ | NET December 2022
The main function of the microkernel is to provide a communication facility between the _______ program and the various _______ that are also running in user space .
i ➥ Virtual, processes
ii ➥ System, processes
iii ➥ Client, services
iv ➥ Virtual, services
Best Explanation:
Answer: (iii)
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Q3➡ | NET December 2022
Consider an operating system capable of loading and executing a single sequential user process at a time. The disk head scheduling algorithm used is first come first served (FCFS) . if FCFS is replaced by shorted seek time first (SSTF) and the vendor claims 50% better benchmark results. What is the expected improvement in the I/O performance of user programs?
i ➥ 50%
ii ➥ 100%
iii ➥ 25%
iv ➥ 0%
Best Explanation:
Answer: (iv)
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Q4➡ | NET December 2022
For the following set of processes scheduled using FCFS policy, determine the average waiting time. Assume that the processes arrived in the order P1, P2, P3, P4.
For the following set of processes scheduled using FCFS policy, determine the average waiting time. Assume that the processes arrived in the order P1, P2, P3, P4
i ➥ 8
ii ➥ 16
iii ➥ 32
iv ➥ 48
Best Explanation:
Answer: (ii)
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Q5➡ | NET December 2022
Which of the statement is not true in regards to virtual memory?
i ➥ The main objective for using virtual memory is to increase the effective capacity of the memory system
ii ➥ Size of the program can be as large as the size of the secondary memory
iii ➥ Program and data are stored in the secondary memory
iv ➥ None of these
Best Explanation:
Answer: (iv)
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Q6➡ | NET December 2022
Which of the following statements are true?
(A) Shortest remaining time first scheduling may cause starvation
(B) Preemptive scheduling may cause starvation
(C) Round robin is better than FCFS in term of response time
Choose the correct answer from the options given below:
i ➥ A only
ii ➥ B, C only
iii ➥ A, B only
iv ➥ A, B, C
Best Explanation:
Answer: (iv)
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Q7➡ | NET December 2022
In design protocol of critical section problem, each process must ask permission to enter critical section in ……… code, it then executes in the critical section; once it, finishes executes in the critical section it enters the …….. code. The process then enters the……..code.
i ➥ entry section, remainder section, exit section
ii ➥ entry section, exit section, remainder section
iii ➥ remainder section, entry section, exit section
iv ➥ remainder section, exit section, entry section
Best Explanation:
Answer: (ii)
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Q8➡ | NET December 2022
Match List (I) with List (II)
A.	 IPC	I.	Resource Allocation
B.	Demand Paging	II.	Computational speedup 
C. 	 Banker’s Algorithm	III.	Task Control  Block
D. 	 PCB	IV.	Virtual Memory
Choose the correct answer from the options given below:
i ➥ A-(II), B-(I), C-(IV), D-(III)
ii ➥ A-(II), B-(IV), C-(I), D-(III)
iii ➥ A-(I), B-(II), C-(III), D-(IV)
iv ➥ A-(II), B-(III), C-(I), D-(IV)
Best Explanation:
Answer: (ii)
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Q9➡ | NET December 2022
Select the correct order of events after power is initialized on a system:
(A) Bootstrap loader is loaded from the disk
(B) Kernel is loaded onto the memory
(C) Firmware ROM loads boot block
Choose the correct answer from the options given below:
i ➥ B, C, A
ii ➥ C, A, B
iii ➥ A, B, C
iv ➥ A, C, B
Best Explanation:
Answer: (ii)
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Q10➡ | NET December 2022
An OS follows round robin scheduling with time quantum of 4 ms. Assuming that the CPU is free now and there are 20 processes waiting in the ready queue, the maximum amount of time that a process waits before getting into the CPU is………….
i ➥ 80 ms
ii ➥ 76 ms
iii ➥ 84 ms
iv ➥ None of the above
Best Explanation:
Answer: (ii)
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Q11➡ | NET June 2022
If an operating system does not allow a child process to exist when the parent process has been terminated, this phenomenon is called as –
i ➥ Threading
ii ➥ Cascading termination
iii ➥ Zombie termination
iv ➥ Process killing
Best Explanation:
Answer: (ii)
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Q12➡ | NET June 2022
For the following page reference string 4, 3, 2, 1, 4, 3, 5, 4, 3, 2, 1, 5 the number of page faults that occur in Least Recently Used (LRU) page replacement algorithm with frame size 3 is
i ➥ 6
ii ➥ 8
iii ➥ 10
iv ➥ 12
Best Explanation:
Answer: (iii)
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Q13➡ | NET June 2022
what is called journaling in Linux operating system?
i ➥ Process scheduling
ii ➥ File saving as transaction
iii ➥ A type of thread
iv ➥ An editor
Best Explanation:
Answer: (ii)
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Q14➡ | NET June 2022
(A)	Stack algorithm	(I)	Deadlock
(B)	Elevator algorithm	(II)	Disk scheduling
(C)	Priority scheduling algorithm	(III)	Page replacement
(D)	Havender’s algorithms	(IV)	CPU scheduling
i ➥ (A)-(III),(B)-(II),(C)-(IV),(D)-(I)
ii ➥ (A)-(II),(B)-(III),(C)-(IV),(D)-(I)
iii ➥ (A)-(III),(B)-(II),(C)-(I),(D)-(IV)
iv ➥ (A)-(II),(B)-(III),(C)-(I),(D)-(IV)
Best Explanation:
Answer: (i)
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Q15➡ | NET June 2022
(A)	Least frequently used				(I) memory is distributed among processors
(B)	Critial section 					(II) Page replacement policy in cache memory
(C)	Loosely coupled multiprocessor system		(III) program section that one begin must complete execution
						       before another processor access the same shared resource
(D)	Distributed operating system organization 	(IV) O/S routines are distributed among available processors.
i ➥ (A)-(III),(B)-(II),(C)-(IV),(D)-(I)
ii ➥ (A)-(I),(B)-(II),(C)-(III),(D)-(IV)
iii ➥ (A)-(II),(B)-(III),(C)-(I),(D)-(IV)
iv ➥ (A)-(II),(B)-(I),(C)-(III),(D)-(IV)
Best Explanation:
Answer: (iii)
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Q16➡ | NET June 2022
(A)	Firmware                                   (I) Number of logical records into physical block
(B)	Batch file                                   (II) ASCII Format
(C)	Packing                                     (III) Resource allocation 
(D)	Bankers algorithm                     (IV) ROM
i ➥ (A)-(II),(B)-(I),(C)-(IV),(D)-(III)
ii ➥ (A)-(II),(B)-(I),(C)-(III),(D)-(IV)
iii ➥ (A)-(IV),(B)-(II),(C)-(I),(D)-(III)
iv ➥ (A)-(IV),(B)-(I),(C)-(II),(D)-(III)
Best Explanation:
Answer: (iii)
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Q1➡ | NET June 2021
Given memory access time as p nanoseconds and additional q nanoseconds for handling the page fault. What is the effective memory access time if a page fault occurs once for every 100 instructions?
i ➥
ii ➥
iii ➥
iv ➥
Answer: I
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Q2➡ | NET June 2021
In a file allocation system, the following allocation schemes are used:
A. Contiguous
B. Indexed
C. Linked allocation
Which of the allocation scheme(s) given above will not suffer from external fragmentation?
Choose the correct answer from the options given below:
i ➥ A and B only
ii ➥ A only
iii ➥ B and C only
iv ➥ C only

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Answer: III
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Q3➡ | NET June 2021
Match List I with List II

Choose the correct answer from the options given below:
i ➥ A – II , B – III , C – IV , D – I
ii ➥ A – IV , B – I , C – II , D – III
iii ➥ A – IV , B – III , C – I , D – II
iv ➥ A – IV , B – III , C – II, D – I

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Answer: III
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Q4➡ | NET June 2021
Consider the following 3 processes with the length of the CPU burst time given in milliseconds:

What is the average waiting time for these processes if they are scheduled using preemptive shortest job first scheduling algorithm?
i ➥ 2.66
ii ➥ 4.66
iii ➥ 5.5
iv ➥ 6
Answer: II
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Q5➡ | NET June 2021
Comprehension: Q5 to Q9
Read the following and answer the questions:
Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine.
If a process of size 34KB is to be executed on this machine, then what will be the size of internal fragmentation for this process?
i ➥ 1KB
ii ➥ 2KB
iii ➥ 4KB
iv ➥ Zero
Answer: II
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Q6➡ | NET June 2021
Comprehension: Q5 to Q9
Read the following and answer the questions:
Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine.
What is the size of page table for handling the given virtual address space, given that each page table entry is of size 2 bytes?
i ➥ 12KB
ii ➥ 2KB
iii ➥ 2MB
iv ➥ 32MB
Answer: III
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Q7➡ | NET June 2021
Comprehension: Q5 to Q9
Read the following and answer the questions:
Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine.
What is the minimum number of bits needed for the physical address?
i ➥ 12
ii ➥ 24
iii ➥ 28
iv ➥ 34
Answer: IV
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Q8➡ | NET June 2021
Comprehension: Q5 to Q9
Read the following and answer the questions:
Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine.
The number of bits reserved for the frame offset is __________.
i ➥ 12
ii ➥ 14
iii ➥ 32
iv ➥ 8
Answer: I
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Q9➡ | NET June 2021
Comprehension: Q5 to Q9
Read the following and answer the questions:
Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine.
Find number of pages required for the given virtual address space?
i ➥ 210
ii ➥ 212
iii ➥ 220
iv ➥ 230
Answer: III
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Q10➡ | UGC NET November 2020
Suppose you have a Linux file system where the block size is 2K bytes, a disk address is 32 bits, and i-node contains the disk addresses of the first 12 direct blocks of file, a single indirect block, and a double indirect block. Approximately, what is the largest file that can be represented by an i-node?
i ➥ 513 Kbytes
ii ➥ 513 Mbytes
iii ➥ 537 Mbytes
iv ➥ 537 KBytes
Answer: II
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Q11➡ | UGC NET November 2020
Which of the following cloud concept/s is/are related to pooling and sharing of resources?
A) Virtual Memory
B) Service
C) Virtualization
Choose the correct answer from the options given below:
i ➥ (C) only
ii ➥ (A) and (B) only
iii ➥ (A) only
iv ➥ (B) only

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Answer: I
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Q12➡ | UGC NET November 2020
Assuming that the system call fork () never fails, consider the following C programs P1 and P2 executed on a UNIX/ Linux system:

Statement I: P1 displays “Happy” 8 times.
Statement II: P2 displays “Happy” 12 times.
In the light of the above statements, choose the correct answer from the options given below:
i ➥ Both Statement I and Statement II are true
ii ➥ Both Statement I and Statement II are false
iii ➥ Statement I is correct but Statement II is false
iv ➥ Statement I is incorrect but Statement II is true

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Answer: III
Explanation:
Fork is the primary method of process creation on Unix-like operating systems. Fork system call is used for creating a new process, which is called child process, which runs concurrently with the process that makes the fork() call (parent process).When fork() is called, parent & child process is run concurrently & complete program is executed for both parent process & child process.
For P1: 

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Q13➡ | UGC NET November 2020
Consider a hypothetical machine with 3 pages of physical memory, 5 pages of virtual memory, and < A,B,C,D,A,B,E,A,B,C,D,E,B,A,B> as the stream of page reference by an application. if P and Q are the number of page faults that the application would incur with FIFO and LRU page replacement algorithms respectively, then (P,Q)=_________(Assuming enough space for storing 3 page frames)
i ➥ (11,10)
ii ➥ (12,11)
iii ➥ (10,11)
iv ➥ (11,12)

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Answer: IV
Explanation:

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Q14➡ | UGC NET November 2020
Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to adjacent one and Shortest Seek Time First (SSTF) algorithm is used?
i ➥ 240 milliseconds
ii ➥ 96 milliseconds
iii ➥ 120 milliseconds
iv ➥ 112 milliseconds

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Answer: III
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Q15➡ | UGC NET November 2020
Which of the following statements with respect to the multiprocessor system are true?
A) Multiprocessor system is controlled by one operating system.
B) In a Multiprocessor system, multiple computers are connected by means of communication lines.
C) Multiprocessor system is classified as multiple instruction streams and multiple data stream systems.

Choose the correct answer from the options given below
i➥ (A) only
ii ➥ (A) and (B) Only
iii ➥ (A) and (C) only
iv ➥ (B) and (C) only

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Answer: III
Explanation:

Multiprocessor System: a multiprocessor is a computer system having two or more processing units (multiple processors) each sharing main memory and peripherals, in order to simultaneously process programs.
(A) True : Multiprocessor system is controlled by one operating system.
(B) False: In a Multiprocessor system, single computer (or Operating system) have multiple processor.
(C) True: Multiprocessor system is classified as multiple instruction streams and multiple data stream systems.

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Q16➡ | UGC NET December 2019

Find average turnaround time and average waiting time using round robin CPU scheduling?
i ➥ 4, 0
ii ➥ 5.66, 1.66
iii ➥ 5.66, 0
iv ➥ 7, 2

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Answer: II
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Q17➡ | UGC NET December 2019
Suppose a system has 12 magnetic tape drives and at time t0, three processes are allotted tape drives out of their need as given below: At time t0, the system is in safe state.
Suppose a system has 12 magnetic tape drives and at time t0, three processes are allotted tape drives out of their need as given below: At time t0, the system is in safe state.   Which of the following is safe sequence so that deadlock is avoided?
Which of the following is safe sequence so that deadlock is avoided?
i ➥ (p0, p1, p2)
ii ➥ (p1, p0, p2)
iii ➥ (p2, p1, p0)
iv ➥ (p0, p2, p1)

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Answer: II
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Q18➡ | UGC NET December 2019
Identify the circumstances under which preemptive CPU scheduling is used :
(a) A process switches from Running state to Ready state
(b) A process switches from Waiting state to Ready state
(c) A process completes its execution
(d) A process switches from Ready to Waiting state
Choose the correct option:
i ➥ (a) and (b) only
ii ➥ (a) and (d) only
iii ➥ (c) and (d) only
iv ➥ (a), (b), (c) only

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Answer: I
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Q19➡ | UGC NET December 2019
Which of the following inter-process communication model is used to exchange messages among co-operative processes?
i ➥ Shared memory model
ii ➥ Message passing model
iii ➥ Shared memory and message passing model.
iv ➥ Queues

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Answer: III
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Q20➡ | UGC NET December 2019
A counting semaphore is initialized to 8. 3 wait() operations and 4 signal() operations are applied. Find the current value of semaphore variable
i ➥ 9
ii ➥ 5
iii ➥ 1
iv ➥ 4

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Answer: I
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Q21➡ | UGC NET December 2019
Consider the following statements :
(a) Windows Azure is a cloud-based operating system.
(b) Google App Engine is an integrated set of online services for consumers to communicate and share with others.
(c) Amazon Cloud Front is a web service for content delivery.
Which of the statements is (are) correct?
i ➥ Only (a) and (b)
ii ➥ Only (a) and (c)
iii ➥ Only (b) and (c)
iv ➥ (a), (b) and (c)

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Answer: II
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Q22➡ | UGC NET December 2019
Which of the following CPU scheduling algorithms is/are supported by LINUX operating system?
i ➥ Non-preemptive priority scheduling
ii ➥ Preemptive priority scheduling and time sharing CPU scheduling
iii ➥ Time sharing scheduling only
iv ➥ Priority scheduling only

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Answer: II
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Q23➡ | UGC NET December 2019
Which of the following methods are used to pass any number of parameters to the operating system through system calls?
i ➥ Registers
ii ➥ Block or table in main memory
iii ➥ Stack
iv ➥ Block in main memory and stack

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Answer: IV
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Q24➡ | UGC NET June 2019
A computer has six tapes drives with n processes competing for them. Each process may need two drives. What is the maximum value of n for the system to be deadlock free?
i ➥ 5
ii ➥ 4
iii ➥ 3
iv ➥ 6

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Answer: I
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Q25➡ | UGC NET June 2019
Match List-I with List-II

Choose the correct option from those given below:
i ➥ (a)-(i); (b)-(ii); (c)-(iii); (d)-(iv)
ii ➥ (a)-(iii); (b)-(i); (c)-(iv); (d)-(ii)
iii ➥ (a)-(ii); (b)-(i); (c)-(iv); (d)-(iii)
iv ➥ (a)-(ii); (b)-(iv); (c)-(iii);(d)-(i)

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Answer: II
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Q26➡ | UGC NET June 2019
Consider a disk system with 100 cylinders. The requests to access the cylinders occur in the following sequence:
4,34,10,7,19,73,2,15,6,20
Assuming that the head is current at cylinder 50, what is the time taken to satisfy all requests if it takes 1ms to move from the cylinder to adjacent one and the shortest seek time first policy is used?
i ➥ 357 ms
ii ➥ 238 ms
iii ➥ 276 ms
iv ➥ 119 ms

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Answer: IV
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Q27➡ | UGC NET June 2019
At a particular time of computation, the value of a counting semaphore is 7. Then 20 P(wait) operations and 15 V(signal) operations are completed on this semaphore. What is the resulting value of the semaphore?
i ➥ 28
ii ➥ 12
iii ➥ 2
iv ➥ 42

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Answer: III
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Q28➡ | UGC NET June 2019
Consider three intensive processes, which requires 10,20 and 30 units of time and arrive at times 0,2 and 6 respectively. how many context switches are needed if the operating system implements a shortest remaining time first scheduling algorithm? Do not count the context switches at time zero ad at the end
i ➥ 4
ii ➥ 2
iii ➥ 3
iv ➥ 1

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Answer: II
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Q29➡ | UGC NET June 2019
Consider that a process has been allocated 3 frames and has a sequence of page referencing 1,2,1,3,7,4,5,6,3,1
What shall be the difference i page faults for the above string using the algorithm of LRU and Optimal page replacement for referencing the string?
i ➥ 2
ii ➥ 0
iii ➥ 1
iv ➥ 3

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Answer: I
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Q30➡ | UGC NET June 2019
The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by
i ➥ Page size
ii ➥ Physical size of memory
iii ➥ The instruction set architecture
iv ➥ Number of processes in memory

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Answer: III
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Q31➡ | UGC NET June 2019
A processor can support a maximum memory of 4 GB where memory is word addressable and a word is 2 bytes. What will be the size of the address bus of the processor?
i ➥ At least 28 bits
ii ➥ At least 2 bytes
iii ➥ At least 31 bits
iv ➥ Minimum 4 bytes

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Answer: III
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Q32➡ | UGC NET June 2019
Which of the following UNIX/Linux pipes will count the number of lines in all the files having .c and .h as their extension in the current working directory?
i ➥ cat *.ch | wc -l
ii ➥ cat *.[c-h] | wc -l
iii ➥ cat *.[ch] | ls -l
iv ➥ cat *.[ch] | wc -l

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Answer: IV
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Q33➡ | UGC NET June 2019
Which of the following are not shared by the threads of the same process?
(a) Stack
(b) Registers
(c) Address Space
(d) Message Queue
i ➥ (a) and (d)
ii ➥ (b) and (c)
iii ➥ (a) and (b)
iv ➥ (a), (b) and (c)

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Answer: III
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Q34➡ | UGC NET December 2018
Suppose a system has 12 instances of some resources with n processes competing for that resource. Each process may require 4 instances of the resource. The maximum value of n for which the system never enters into deadlock is
i ➥ 3
ii ➥ 4
iii ➥ 5
iv ➥ 6

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Answer: I
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Q35➡ | UGC NET December 2018
Suppose P,Q and R are co-operating processes satisfying Mutual Exclusion condition. Then if the process Q is executing in its critical section then
i ➥ ‘P’ executes in critical section
ii ➥ ‘R’ executes in critical section
iii ➥ Neither ‘P’ nor ‘R’ executes in their critical section
iv ➥ Both ‘P’ and ‘R’ executes in critical section

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Answer: III
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Q36➡ | UGC NET December 2018
A Computer uses a memory unit with 256K word of 32 bits each. A binary instruction code is stored in one word of memory. The instruction has four parts: an indirect bit, an operation code and a register code part to specify one of 64 registers and an address part. How many bits are there in operation code, the register code part and the address part?
i ➥ 7,7,18
ii ➥ 18,7,7
iii ➥ 7,6,18
iv ➥ 6,7,18

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Answer: III
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Q37➡ | UGC NET December 2018
Consider the following set of processes and the length of CPU burst time given in milliseconds:

Assume that processes being scheduled with Round-Robin Scheduling Algorithm with Time Quantum 4ms. Then The waiting time for P4 is_______ms.
i ➥ 0
ii ➥ 4
iii ➥ 12
iv ➥ 6

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Answer: III
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Q38➡ | UGC NET December 2018
Consider a system with 2 level cache. Access times of Level 1, Level 2 cache and main memory are 0.5 ns, 5 ns and 100 ns respectively. The hit rates of Level1 and Level2 caches are 0.7 and 0.8 respectively. What is the average access time of the system ignoring the search time within cache?
i ➥ 20.75 ns
ii ➥ 7.55 ns
iii ➥ 24.35 ns
iv ➥ 35.20 ns

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Answer: II
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Q39➡ | UGC NET December 2018
Consider a disk pack with 32 surfaces, 64 tracks and 512 sectors per pack. 256 bytes of data are stored in a bit serial manner in a sector. The number of bits required to specify a particular sector in the disk is
i ➥ 19
ii ➥ 20
iii ➥ 18
iv ➥ 22

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Answer: II
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Q40➡ | UGC NET December 2018
Dirty bit is used to show the
i ➥ Page with low frequency occurrence
ii ➥ Wrong page
iii ➥ Page with corrupted data
iv ➥ Page that is modified after being loaded into cache memory

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Answer: IV
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Q41➡ | UGC NET December 2018
In Linux operating system environment____________command is used to print a file.
i ➥ print
ii ➥ lpr
iii ➥ ptr
iv ➥ pr

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Answer: II
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Q42➡ | UGC NET December 2018
Suppose for a process P, reference to pages in order are 1, 2, 4, 5,2,1,2,4. Assume that main memory can accommodate 3 pages and the main memory has already pages 1 and 2 in the order 1 – first, 2- second. At this moment, assume FIFO Page Replacement Algorithm is used then the number of page faults that occur to complete the execution of process P is
i ➥ 6
ii ➥ 4
iii ➥ 3
iv ➥ 5

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Answer: IV
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Q43➡ | UGC NET December 2018
________system call creates new process in Unix.
i ➥ fork
ii ➥ fork new
iii ➥ create
iv ➥ create new

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Answer: I
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Q44➡ | UGC NET December 2018
A process residing in main memory and ready and waiting for execution, is kept on
i ➥ Job Queue
ii ➥ Execution Queue
iii ➥ Wait Queue
iv ➥ Ready Queue

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Answer: IV
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Q45➡ | UGC NET June 2018
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 :
i ➥ 8
ii ➥ 9
iii ➥ 11
iv ➥ 10

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Answer: II
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Q46➡ | UGC NET June 2018
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
i ➥
ii ➥ 68
iii ➥ 75
iv ➥ 78

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Answer: IV
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Q47➡ | UGC NET June 2018
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 __
i ➥ e-15
ii ➥ 1-e-15
iii ➥ 1-e-20
iv ➥ e-20

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Answer: IV
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Q48➡ | UGC NET June 2018
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 ?
i ➥ I/O protection is ensured by operating system routines.
ii ➥ I/O protection is ensured by a hardware trap.
iii ➥ I/O protection is ensured during system configuration.
iv ➥ I/O protection is not possible.

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Answer: I
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Q49➡ | UGC NET June 2018
Which UNIX/Linux command is used to make all files and sub-directories in the directory “progs” executable by all users ?
i ➥ chmod− R a+x progs
ii ➥ chmod −R 222 progs
iii ➥ chmod−X a+x progs
iv ➥ chmod −X 222 progs

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Answer: I
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Q50➡ | UGC NET June 2018
Which of the following statements are true ?
(i) External Fragmentation exists when there is enough total memory space to satisfy a request but the available space is contiguous.
(ii) Memory Fragmentation can be internal as well as external.
(iii) One solution to external Fragmentation is compaction.
Code:
i ➥ (a) and (b) only
ii ➥ (a) and (c) only
iii ➥ (b) and (c) only
iv ➥ (a), (b) and (c)

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Answer: III
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Q51➡ | UGC NET June 2018
Page information in memory is also called as Page Table. The essential contents in each entry of a page table is/are .
i ➥ Page Access information
ii ➥ Virtual Page number
iii ➥ Page Frame number
iv ➥ Both virtual page number and Page Frame Number

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Answer: III
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Q52➡ | UGC NET June 2018
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 .
i ➥ 5
ii ➥ 7
iii ➥ 9
iv ➥ 10

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Answer: II
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Q53➡ | UGC NET June 2018
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
i ➥
ii ➥
iii ➥
iv ➥

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Answer: II
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Q54➡ | UGC NET June 2018
In which of the following scheduling criteria, context switching will never take place ?
i ➥ ROUND ROBIN
ii ➥ Preemptive SJF
iii ➥ Non-preemptive SJF
iv ➥ Preemptive priority

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Answer: III
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