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UGC NET · PAPER 2

UGC NET Paper 2 Computer Science – Operating Systems PYQ: OS Structure & Miscellaneous

26 questions · answer key at the end · updated 1 Oct 2026
Q1.
In Linux, where is the user password stored?
  1. (A) /etc/password
  2. (B) /root/password
  3. (C) /etc/passwd
  4. (D) /root/passwd
Answer & explanation →
Q2.
A program that is used by other routines to accomplish a particular task is called:
  1. (A) Micro program
  2. (B) Micro operation
  3. (C) Routine
  4. (D) Subroutine
Answer & explanation →
Q3.
The following table shows the time between failures (in hours) observed for a piece of software:
Error number12345
Time since last failure (hours)64856
Assuming an exponential reliability model, what is the reliability of the system for one hour of operation?
  1. (A) e^(-9/29)
  2. (B) e^(-7/29)
  3. (C) e^(-5/29)
  4. (D) e^(-3/29)
Answer & explanation →
Q4.
Consider the following statements about a software product line system:
Statement I: At the interaction level, components provide an operator display interface and an interface with the communication system used.
Statement II: At the I/O management level, components handle operator authentication, report generator and query manager.
  1. (A) Both Statement I and Statement II are correct
  2. (B) Both Statement I and Statement II are incorrect
  3. (C) Statement I is correct but Statement II is incorrect
  4. (D) Statement I is incorrect but Statement II is correct
Answer & explanation →
Q5.
Consider the following statements:
S1: The LRU page replacement algorithm suffers from Belady's anomaly.
S2: Shortest-remaining-time-first scheduling may cause starvation.
S3: The stack is shared by all threads in a process.
  1. (A) S1, S2 and S3 are true
  2. (B) S1, S3 are false and S2 is true
  3. (C) S1, S2 are false and S3 is true
  4. (D) S1, S2 and S3 are false
Answer & explanation →
Q6.
Consider the following statements:
S1: The LRU page replacement algorithm suffers from Belady's anomaly.
S2: Shortest-remaining-time-first scheduling may cause starvation.
S3: The stack is shared by all threads in a process.
  1. (A) S1, S2 and S3 are true
  2. (B) S1, S3 are false and S2 is true
  3. (C) S1, S2 are false and S3 is true
  4. (D) S1, S2 and S3 are false
Answer & explanation →
Q7.
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.
  1. (A) Virtual, processes
  2. (B) System, processes
  3. (C) Client, services
  4. (D) Virtual, services
Answer & explanation →
Q8.
Match List I with List II:
List I: (A) IPC (B) Demand Paging (C) Banker's Algorithm (D) PCB
List II: (I) Resource Allocation (II) Computational speedup (III) Task Control Block (IV) Virtual Memory
Choose the correct match from A-D to I-IV.
  1. (A) A-(II), B-(I), C-(IV), D-(III)
  2. (B) A-(II), B-(IV), C-(I), D-(III)
  3. (C) A-(I), B-(II), C-(III), D-(IV)
  4. (D) A-(II), B-(III), C-(I), D-(IV)
Answer & explanation →
Q9.
Select the correct order of events after power is applied to a system:
(A) Bootstrap loader is loaded from the disk.
(B) Kernel is loaded into memory.
(C) Firmware ROM loads the boot block.
  1. (A) B, C, A
  2. (B) C, A, B
  3. (C) A, B, C
  4. (D) A, C, B
Answer & explanation →
Q10.
Match List I with List II:
List I: (A) Stack algorithm (B) Elevator algorithm (C) Priority scheduling algorithm (D) Havender's algorithm
List II: (I) Deadlock (II) Disk scheduling (III) Page replacement (IV) CPU scheduling
Choose the correct match from A-D to I-IV.
  1. (A) A-(III), B-(II), C-(IV), D-(I)
  2. (B) A-(II), B-(III), C-(IV), D-(I)
  3. (C) A-(III), B-(II), C-(I), D-(IV)
  4. (D) A-(II), B-(III), C-(I), D-(IV)
Answer & explanation →
Q11.
Match List I with List II.
List I: (A) Least frequently used (B) Critical section (C) Loosely coupled multiprocessor system (D) Distributed operating system organization
List II: (I) Memory is distributed among the processors (II) Page replacement policy in cache memory (III) Program section that one process must completely execute before another process can access the same shared resource (IV) O/S routines are distributed among the available processors
Choose the correct answer from the options given below.
  1. (A) (A)-(III), (B)-(II), (C)-(IV), (D)-(I)
  2. (B) (A)-(I), (B)-(II), (C)-(III), (D)-(IV)
  3. (C) (A)-(II), (B)-(III), (C)-(I), (D)-(IV)
  4. (D) (A)-(II), (B)-(I), (C)-(III), (D)-(IV)
Answer & explanation →
Q12.
Match List I with List II.
List I: (A) Firmware (B) Batch file (C) Packing (D) Banker's algorithm
List II: (I) Number of logical records packed into a physical block (II) File kept in ASCII format (III) Resource allocation (deadlock-avoidance) technique (IV) Program/data permanently stored in ROM
Choose the correct answer from the options given below.
  1. (A) (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
  2. (B) (A)-(II), (B)-(I), (C)-(III), (D)-(IV)
  3. (C) (A)-(IV), (B)-(II), (C)-(I), (D)-(III)
  4. (D) (A)-(IV), (B)-(I), (C)-(II), (D)-(III)
Answer & explanation →
Q13.
Match List I with List II.
List I (system call): (A) fork() (B) exec() (C) kill() (D) exit()
List II (description): (I) Sends a signal from one process to another process (II) Indicates termination of the current process (III) Loads the specified program into memory (IV) Creates a child process
Choose the correct answer from the options given below.
  1. (A) (A)-(II), (B)-(III), (C)-(IV), (D)-(I)
  2. (B) (A)-(IV), (B)-(I), (C)-(II), (D)-(III)
  3. (C) (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
  4. (D) (A)-(IV), (B)-(III), (C)-(II), (D)-(I)
Answer & explanation →
Q14.
Which of the following cloud computing concept(s) is/are related to the pooling and sharing of resources?
(A) Virtual Memory
(B) Service
(C) Virtualization
  1. (A) (C) only
  2. (B) (A) and (B) only
  3. (C) (A) only
  4. (D) (B) only
Answer & explanation →
Q15.
Which of the following routing technique(s) is/are used in distributed systems?
(A) Fixed Routing
(B) Virtual Routing
(C) Dynamic Routing
  1. (A) (A) only
  2. (B) (A) and (B) only
  3. (C) (C) only
  4. (D) All of (A), (B) and (C)
Answer & explanation →
Q16.
Match the following WINDOWS system calls with the equivalent UNIX system calls, with reference to process control and file manipulation:
Windows: (A) CreateProcess() (B) WaitForSingleObject() (C) CreateFile() (D) CloseHandle()
UNIX: (I) open() (II) close() (III) fork() (IV) wait()
  1. (A) A-III, B-IV, C-I, D-II
  2. (B) A-IV, B-III, C-I, D-II
  3. (C) A-IV, B-III, C-II, D-I
  4. (D) A-III, B-IV, C-II, D-I
Answer & explanation →
Q17.
Which statement is not correct about the 'init' process in UNIX?
  1. (A) It is generally the parent of the login shell.
  2. (B) It has PID 1.
  3. (C) It is the first process in the system.
  4. (D) Init forks and execs a 'getty' process at every port connected to a terminal.
Answer & explanation →
Q18.
Which UNIX command correctly changes the case of only the first three lines of the file "shortlist" from lower case to upper case?
  1. (A) $ tr '[a-z]' '[A-Z]' shortlist | head -3
  2. (B) $ head -3 shortlist | tr '[a-z]' '[A-Z]'
  3. (C) $ tr head -3 shortlist '[A-Z]' '[a-z]'
  4. (D) $ tr shortlist head -3 '[a-z]' '[A-Z]'
Answer & explanation →
Q19.
Match the following basic vi editor commands in UNIX with their functions.
List I (Command): (a) dd (b) yy (c) p (d) u
List II (Function): (i) Copies (yanks) the current line into the buffer (ii) Undoes the last change made to the file (iii) Deletes the current line (iv) Pastes the buffer's contents after the cursor
Choose the correct match from the options given below.
  1. (A) (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
  2. (B) (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
  3. (C) (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
  4. (D) (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
Answer & explanation →
Q20.
Consider the following statements about linker software: (I) A linker combines multiple object (relocatable) modules into a single load module. (II) A linker replaces absolute references in a program with symbolic references. Which of the above statement(s) is/are correct?
  1. (A) Only I
  2. (B) Only II
  3. (C) Both I and II
  4. (D) Neither I nor II
Answer & explanation →
Q21.
A distributed operating system typically consists of:
  1. (A) Loosely coupled O.S. software on loosely coupled hardware
  2. (B) Loosely coupled O.S. software on tightly coupled hardware
  3. (C) Tightly coupled O.S. software on loosely coupled hardware
  4. (D) Tightly coupled O.S. software on tightly coupled hardware
Answer & explanation →
Q22.
Which of the following statements about UNIX signals is NOT correct?
  1. (A) The INT signal is sent by the terminal driver when one types the interrupt character (e.g. Ctrl-C), requesting termination of the current operation.
  2. (B) TERM is a request to terminate execution completely; the receiving process cleans up its state and exits.
  3. (C) QUIT is similar to TERM, except that it defaults to producing a core dump if not caught.
  4. (D) KILL is a blockable signal.
Answer & explanation →
Q23.
A null remote procedure call (RPC) (carrying 0 data bytes) takes 1.0 msec, with an additional 1.5 msec for every 1K of data carried. How long does it take to read 32K from a file server, issued as 32 separate 1K RPCs?
  1. (A) 49 msec
  2. (B) 80 msec
  3. (C) 48 msec
  4. (D) 100 msec
Answer & explanation →
Q24.
What is the function of the following UNIX command?
wc -l a > b &
  1. (A) It runs the word-count program to count the number of lines in its input, file a, writing the result to file b, as a foreground process.
  2. (B) It runs the word-count program to count the number of lines in its input, file a, writing the result to file b, but does it as a background process.
  3. (C) It counts the errors during the execution of a process, a, and puts the result in process b.
  4. (D) It copies a number of lines of a program from file a and stores them in file b.
Answer & explanation →
Q25.
Which of the following statements about the cron daemon in a UNIX operating system is NOT correct?
  1. (A) cron is the standard tool for running commands on a predetermined schedule.
  2. (B) It starts when the system boots and keeps running as long as the system stays up.
  3. (C) cron reads configuration files (crontabs) that list command lines together with the times at which they should be invoked.
  4. (D) Crontabs for individual users are not stored.
Answer & explanation →
Q26.
In UNIX, which single command creates the directory "PIS" together with its two subdirectories "progs" and "data" (i.e. PIS/progs and PIS/data), all newly created in one invocation?
  1. (A) mkdir PIS/progs PIS/data PIS
  2. (B) mkdir PIS progs data
  3. (C) mkdir PIS PIS/progs PIS/data
  4. (D) mkdir PIS/progs data
Answer & explanation →

Answer key

  1. 1 – C
  2. 2 – D
  3. 3 – C
  4. 4 – A
  5. 5 – B
  6. 6 – B
  7. 7 – C
  8. 8 – B
  9. 9 – B
  10. 10 – A
  11. 11 – C
  12. 12 – C
  13. 13 – C
  14. 14 – A
  15. 15 – D
  16. 16 – A
  17. 17 – C
  18. 18 – B
  19. 19 – D
  20. 20 – A
  21. 21 – C
  22. 22 – D
  23. 23 – B
  24. 24 – B
  25. 25 – D
  26. 26 – C