Thrashing

1. What is thrashing in an operating system?

o A) Excessive use of CPU resources

o B) High page fault rate leading to excessive paging

o C) Low memory utilization

o D) Increased process execution time

o Answer: B

2. When does thrashing occur?

o A) When a process is waiting for I/O

o B) When the system has too much free memory

o C) When a process does not have enough frames for its active pages

o D) When all pages are in memory

o Answer: C

3. Which of the following best describes the impact of thrashing on system performance?

o A) It increases system throughput

o B) It leads to high CPU utilization

o C) It decreases system efficiency due to high page faulting

o D) It has no impact on performance

o Answer: C

4. Which model is used to manage thrashing?

o A) Locality Model

o B) FIFO Model

o C) Optimal Page Replacement Model

o D) LRU Model

o Answer: A

5. In the working set model, what does a process's locality refer to?

o A) The number of processes it can run

o B) The set of pages that are frequently accessed

o C) The amount of memory allocated to it

o D) The execution time of the process

o Answer: B
Virtual Memory

6. What is the purpose of virtual memory?

o A) To provide a larger memory space than physically available

o B) To reduce the cost of RAM

o C) To allow multiple users to run processes simultaneously

o D) To improve the speed of I/O operations

o Answer: A

7. In virtual memory systems, what does the term 'paging' refer to?

o A) Dividing physical memory into frames

o B) Dividing logical memory into pages

o C) Copying data to secondary storage

o D) Executing multiple processes

o Answer: B

8. Which of the following statements about demand paging is true?

o A) It loads all pages into memory at startup

o B) It loads pages only when they are accessed

o C) It eliminates the need for page replacement

o D) It reduces the complexity of memory management

o Answer: B

9. What is a page fault?

o A) Accessing a page that is currently in memory

o B) Accessing a page that is not in memory

o C) The process of replacing a page

o D) None of the above

o Answer: B

10. What is the purpose of the page table?

o A) To store process execution history

o B) To map virtual addresses to physical addresses

o C) To manage I/O operations

o D) To allocate CPU time to processes

o Answer: B
Page Replacement Algorithms

11. Which page replacement algorithm replaces the oldest page in memory?

o A) Least Recently Used (LRU)

o B) First-In-First-Out (FIFO)

o C) Optimal

o D) Random

o Answer: B

12. What is Belady's anomaly?

o A) When increasing the number of page frames results in a higher page fault rate

o B) When a page fault occurs

o C) When all pages are in memory

o D) When memory allocation is inefficient

o Answer: A

13. Which of the following algorithms is considered optimal?

o A) FIFO

o B) LRU

o C) Optimal Page Replacement

o D) Second Chance

o Answer: C

14. The Least Recently Used (LRU) algorithm replaces:

o A) The page that has been used the least recently

o B) The page that has been in memory the longest

o C) A randomly selected page

o D) The page with the smallest size

o Answer: A

15. The Second Chance page replacement algorithm is a modification of which algorithm?

o A) LRU

o B) FIFO

o C) Optimal

o D) Random

o Answer: B
Segmentation

16. What does segmentation do in memory management?

o A) Divides memory into fixed-size pages

o B) Divides memory into segments based on logical divisions

o C) Combines multiple segments into one

o D) Optimizes disk storage

o Answer: B

17. In segmentation, a logical address is expressed as:

o A) <page number, offset>

o B) <segment number, offset>

o C) <frame number, offset>

o D) <process ID, memory location>

o Answer: B

18. Which of the following is an advantage of segmentation?

o A) No external fragmentation

o B) Simplified memory allocation

o C) Better alignment with user views of processes

o D) Increased internal fragmentation

o Answer: C

19. What is the main disadvantage of segmentation?

o A) Increased internal fragmentation

o B) External fragmentation

o C) Complexity in addressing

o D) Reduced performance

o Answer: B

20. Modern operating systems typically use:

o A) Only paging

o B) Only segmentation

o C) A combination of paging and segmentation

o D) None of the above

o Answer: C
Process Management

21. What is a process in an operating system?

o A) A program in execution

o B) A set of instructions

o C) A type of hardware

o D) A memory allocation unit

o Answer: A

22. Which of the following is a state of a process?

o A) New

o B) Ready

o C) Running

o D) All of the above

o Answer: D

23. What does the 'ready' state indicate for a process?

o A) The process is currently executing

o B) The process is waiting for I/O

o C) The process is prepared to execute

o D) The process has been terminated

o Answer: C

24. What is the purpose of process scheduling?

o A) To manage memory

o B) To determine which process runs at a given time

o C) To handle input and output

o D) To allocate disk space

o Answer: B

25. Which of the following is a common scheduling algorithm?

o A) Shortest Job First (SJF)

o B) First-Come, First-Served (FCFS)

o C) Round Robin (RR)

o D) All of the above

o Answer: D
CPU Scheduling

26. What is the main goal of CPU scheduling?

o A) To maximize CPU utilization

o B) To minimize response time

o C) To optimize throughput

o D) All of the above

o Answer: D

27. In Round Robin scheduling, each process is given:

o A) A fixed time slice

o B) Unlimited time

o C) The time needed to complete

o D) No time at all

o Answer: A

28. Which scheduling algorithm is most suitable for batch processing?

o A) Round Robin

o B) Shortest Job First (SJF)

o C) Priority Scheduling

o D) Multilevel Queue Scheduling

o Answer: B

29. In a multi-level queue scheduling algorithm:

o A) Processes are permanently assigned to one queue

o B) All processes are treated equally

o C) There is a single queue for all processes

o D) Processes can move between queues

o Answer: A

30. What is priority inversion?

o A) When a low-priority process runs before a high-priority process

o B) When multiple processes have the same priority

o C) When the CPU is idle

o D) None of the above

o Answer: A
Synchronization

31. What is the purpose of process synchronization?

o A) To ensure correct execution of processes accessing shared resources

o B) To increase CPU utilization

o C) To reduce memory usage

o D) To speed up I/O operations

o Answer: A

32. Which of the following is a synchronization primitive?

o A) Mutex

o B) Semaphore

o C) Monitor

o D) All of the above

o Answer: D

Synchronization

34. Which of the following describes a semaphore?

o A) A special type of mutex that allows multiple threads to access a resource

o B) A mechanism that allows processes to communicate with each other

o C) A structure that holds the state of a process

o D) A hardware interrupt mechanism

o Answer: A

35. What is a deadlock?

o A) A state where processes cannot proceed because they are waiting for each other

o B) A situation where a process is terminated

o C) A scenario where the CPU is idle

o D) None of the above

o Answer: A

36. Which of the following conditions is NOT necessary for a deadlock to occur?

o A) Mutual exclusion

o B) Hold and wait

o C) Preemption

o D) Circular wait
 o Answer: C

37. How can deadlocks be prevented?

o A) By allowing processes to hold multiple resources

o B) By enforcing strict ordering of resource requests

o C) By using non-blocking algorithms

o D) All of the above

o Answer: B

38. In a producer-consumer problem, which synchronization mechanism is commonly used?

o A) Mutex

o B) Semaphore

o C) Condition Variable

o D) All of the above

o Answer: D

Memory Management

39. What is the main goal of memory management in an operating system?

o A) To increase CPU speed

o B) To allocate memory to processes efficiently

o C) To manage file systems

o D) To schedule CPU tasks

o Answer: B

40. Which of the following describes contiguous memory allocation?

o A) Allocating non-contiguous blocks of memory to processes

o B) Assigning a single continuous block of memory to a process

o C) Using paging to divide memory into frames

o D) Allowing processes to share memory

o Answer: B

41. What is fragmentation in memory management?

o A) The division of memory into smaller sections

o B) Inefficient use of memory due to allocation and deallocation

o C) The process of copying data from one location to another

o D) The organization of processes in memory

 o Answer: B

42. Which type of fragmentation occurs when free memory is divided into small blocks?

o A) Internal fragmentation

o B) External fragmentation

o C) Memory pooling

o D) None of the above

o Answer: B

43. What is the purpose of a page replacement algorithm?

o A) To load pages into memory

o B) To decide which pages to remove from memory when new pages need to be
loaded

o C) To allocate memory for processes

o D) To optimize CPU usage

o Answer: B

File Systems

44. What is a file system?

o A) A method for organizing data on a storage device

o B) A way to manage network connections

o C) A structure for handling CPU tasks

o D) A method for executing processes

o Answer: A

45. Which of the following is NOT a file attribute?

o A) Name

o B) Size

o C) Location

o D) Process ID

o Answer: D

46. What is the purpose of a directory in a file system?

o A) To store metadata about files

o B) To group related files and manage file paths

o C) To execute file operations

 o D) To manage memory allocation

o Answer: B

47. In which type of file allocation does the file system allocate contiguous blocks of disk
space?

o A) Linked allocation

o B) Indexed allocation

o C) Contiguous allocation

o D) None of the above

o Answer: C

48. Which file system is known for its journaling feature?

o A) FAT32

o B) NTFS

o C) ext3

o D) Both B and C

o Answer: D

I/O Management

49. What is the purpose of I/O management in an operating system?

o A) To allocate CPU resources

o B) To manage data transfer between the CPU and I/O devices

o C) To handle memory allocation

o D) To schedule processes

o Answer: B

50. Which of the following I/O techniques allows a program to continue executing while
waiting for I/O operations to complete?

o A) Blocking I/O

o B) Non-blocking I/O

o C) Polling

o D) Direct I/O

o Answer: B

51. What is a device driver?

o A) A software component that controls a hardware device

o B) A protocol for network communication

 o C) A memory allocation technique

o D) A type of operating system

o Answer: A

52. Which of the following is an advantage of Direct Memory Access (DMA)?

o A) It reduces CPU overhead during I/O operations

o B) It allows faster data transfer rates

o C) It simplifies I/O operations

o D) All of the above

o Answer: D

53. What does buffering in I/O operations refer to?

o A) Storing data temporarily to accommodate speed differences between I/O devices

and the CPU

o B) Allocating additional memory for processes

o C) The process of compressing data

o D) Managing process priorities

o Answer: A

Advanced Concepts

54. What is the main function of an operating system kernel?

o A) To manage user interfaces

o B) To interact with hardware and manage system resources

o C) To execute applications

o D) To provide networking capabilities

o Answer: B

55. Which of the following is an example of a microkernel?

o A) Linux

o B) Windows NT

o C) QNX

o D) UNIX

o Answer: C

56. What is a system call?

o A) A request made by a user to access system resources

 o B) A request made by a program to the operating system for a service

o C) A method to handle errors in a program

o D) A command executed by the CPU

o Answer: B

57. Which type of operating system allows multiple users to share resources simultaneously?

o A) Real-time OS

o B) Batch OS

o C) Time-sharing OS

o D) Network OS

o Answer: C

58. What is the purpose of a watchdog timer?

o A) To measure system performance

o B) To detect system faults and reset the system if necessary

o C) To manage power consumption

o D) To allocate memory

o Answer: B

General Knowledge

59. Which of the following is NOT a type of operating system?

o A) Batch OS

o B) Time-sharing OS

o C) Resource management OS

o D) Real-time OS

o Answer: C

60. What is the primary role of the command interpreter in an OS?

o A) To execute background processes

o B) To manage user interactions and execute commands

o C) To handle memory allocation

o D) To manage file systems

o Answer: B

Continuing the Question Set

61. Which of the following statements about threads is TRUE?

 o A) Threads cannot share resources with other threads

o B) A thread is a lightweight process

o C) Threads have their own memory space

o D) Threads are slower to create than processes

o Answer: B

62. Which scheduling algorithm is designed to minimize turnaround time?

o A) First-Come, First-Served (FCFS)

o B) Shortest Job First (SJF)

o C) Round Robin (RR)

o D) Priority Scheduling

o Answer: B

63. What is context switching?

o A) Switching between user interfaces

o B) Saving and restoring the state of a CPU so that multiple processes can share a
single CPU

o C) Changing the priority of processes

o D) Transferring data between processes

o Answer: B

64. Which of the following is a disadvantage of a virtual memory system?

o A) It increases the size of the address space

o B) It may lead to thrashing

o C) It improves system performance

o D) It allows multiple processes to run simultaneously

o Answer: B

Buffer Cache and Performance

66. What is the main purpose of a buffer cache in an operating system?

o A) To store the executable files of applications

o B) To reduce the number of disk I/O operations by caching frequently accessed data

o C) To manage the CPU registers

o D) To allocate memory for processes

 o Answer: B

67. Which scheduling algorithm is based on assigning a fixed time slice to each process?

o A) First-Come, First-Served (FCFS)

o B) Shortest Job First (SJF)

o C) Round Robin (RR)

o D) Priority Scheduling

o Answer: C

68. Which of the following is an effect of thrashing?

o A) Increased CPU utilization

o B) Decreased system performance due to excessive paging

o C) Enhanced multitasking capabilities

o D) Reduced memory usage

o Answer: B

Virtual Memory

69. What does the term 'paging' refer to in the context of virtual memory?

o A) The process of saving a file to disk

o B) Dividing virtual memory into fixed-size blocks called pages

o C) The allocation of contiguous memory blocks to processes

o D) None of the above

o Answer: B

70. In a paging system, what is the purpose of a page table?

o A) To manage physical memory

o B) To map virtual addresses to physical addresses

o C) To store process states

o D) To handle interrupts

o Answer: B

71. What is the effect of a page fault?

o A) The system crashes

o B) The process is terminated

o C) The operating system retrieves the missing page from disk

o D) The CPU is reset

 o Answer: C

Security and Protection

72. What is the purpose of access control in an operating system?

o A) To manage system resources

o B) To define who can access certain resources and what actions they can perform

o C) To schedule processes

o D) To optimize memory usage

o Answer: B

73. Which of the following is a common method of protecting system memory?

o A) Segmentation

o B) Data encryption

o C) Compression

o D) Paging

o Answer: A

74. What is the role of user authentication in an operating system?

o A) To manage file access

o B) To verify the identity of users attempting to access the system

o C) To allocate CPU time

o D) To manage memory allocation

o Answer: B

75. Which of the following describes a firewall?

o A) A hardware device that accelerates data processing

o B) A software application that protects the system from unauthorized access

o C) A tool for managing processes

o D) A memory management technique

o Answer: B

Networking and Operating Systems

76. What is the primary function of a network operating system?

o A) To manage local hardware resources

o B) To enable communication between multiple computers and manage network

resources
 o C) To run applications in isolation

o D) To manage CPU scheduling

o Answer: B

77. Which protocol is used for sending error messages and operational information on a
network?

o A) TCP

o B) IP

o C) ICMP

o D) FTP

o Answer: C

78. What does the acronym DHCP stand for?

o A) Dynamic Host Configuration Protocol

o B) Data Handling and Control Protocol

o C) Distributed Host Communication Protocol

o D) Dynamic Host Control Protocol

o Answer: A

Advanced Operating Systems

79. Which of the following is a characteristic of a real-time operating system (RTOS)?

o A) It has high throughput but may have variable response time

o B) It guarantees a specific response time for critical tasks

o C) It is designed for batch processing

o D) It runs only on single-user systems

o Answer: B

80. What is the main goal of a distributed operating system?

o A) To run applications on a single machine

o B) To manage resources across multiple interconnected computers

o C) To optimize the performance of a single CPU

o D) To handle memory management for embedded systems

o Answer: B

81. Which of the following describes a hypervisor?

o A) A system that manages hardware resources for a single operating system

 o B) A software layer that allows multiple operating systems to run on a single
hardware platform

o C) A tool for managing user interfaces

o D) A protocol for network communication

o Answer: B

Miscellaneous

82. Which of the following is a command used to display the current working directory in a
Unix/Linux environment?

o A) cd

o B) pwd

o C) ls

o D) dir

o Answer: B

83. What is a bootloader?

o A) A program that loads an operating system into memory

o B) A tool for managing user permissions

o C) A hardware component of a computer

o D) A type of file system

o Answer: A

84. What is the purpose of system logs in an operating system?

o A) To record system activities and errors

o B) To optimize memory usage

o C) To schedule tasks

o D) To manage user interfaces

o Answer: A

85. Which type of user interface allows users to interact with the operating system using
graphical elements?

o A) Command-Line Interface (CLI)

o B) Graphical User Interface (GUI)

o C) Application Programming Interface (API)

o D) Batch Processing Interface

o Answer: B
 86. In the context of operating systems, what does 'virtualization' refer to?

o A) Running multiple applications simultaneously

o B) Creating a simulated environment for running applications

o C) Using hardware to manage memory

o D) Encrypting data

o Answer: B

87. Which of the following is an example of an embedded operating system?

o A) Windows

o B) Android

o C) iOS

o D) RTOS for a washing machine

o Answer: D

88. What is the primary purpose of an operating system's shell?

o A) To manage hardware resources

o B) To execute commands entered by users

o C) To provide a graphical user interface

o D) To handle file operations

o Answer: B

89. Which of the following can be a consequence of not managing system resources
effectively?

o A) Increased system performance

o B) Resource contention and system crashes

o C) Faster task execution

o D) Enhanced user experience

o Answer: B

PROBLEMS:
Shortest Job First (SJF)
1. In the Shortest Job First (SJF) scheduling algorithm, how is the next process to be executed
determined?

o A) The process with the largest burst time

o B) The process with the shortest burst time

 o C) The process that arrives first in the queue

o D) The process with the highest priority

o Answer: B

2. Which of the following is a disadvantage of the Shortest Job First (SJF) scheduling algorithm?

o A) It can lead to starvation for longer processes

o B) It guarantees the shortest turnaround time

o C) It is easy to implement

o D) It requires minimal CPU utilization

o Answer: A

3. Consider the following processes with their burst times:

o Process P1: 6 ms

o Process P2: 8 ms

o Process P3: 7 ms

o Process P4: 3 ms

o What is the average waiting time using the SJF scheduling algorithm?

o A) 5.5 ms

o B) 7 ms

o C) 6 ms

o D) 4.5 ms

o Answer: A

o Calculation:

 Order: P4 (3), P1 (6), P3 (7), P2 (8)

 Waiting times: P4 = 0, P1 = 3, P3 = 9, P2 = 16

 Average waiting time = (0 + 3 + 9 + 16) / 4 = 7 ms

Round Robin (RR)

4. In the Round Robin scheduling algorithm, what happens if a process does not finish within its
time quantum?

o A) It is terminated immediately

o B) It is put back at the end of the ready queue

o C) It runs until it completes

o D) It is paused indefinitely
 o Answer: B

5. What is the primary advantage of the Round Robin scheduling algorithm?

o A) It minimizes the average waiting time

o B) It provides a fair allocation of CPU time to all processes

o C) It prevents starvation

o D) It is easy to implement

o Answer: B

6. Consider the following processes with burst times and a time quantum of 4 ms:

o Process P1: 8 ms

o Process P2: 4 ms

o Process P3: 9 ms

o Process P4: 5 ms

o What is the average turnaround time using the Round Robin scheduling algorithm?

o A) 11.75 ms

o B) 12.5 ms

o C) 13 ms

o D) 10 ms

o Answer: A

o Calculation:

 Completion times: P1 = 12, P2 = 4, P3 = 20, P4 = 17

 Turnaround times: P1 = 12, P2 = 4, P3 = 20, P4 = 17

 Average turnaround time = (12 + 4 + 20 + 17) / 4 = 13.25 ms

Deadlock

7. Which of the following conditions is NOT necessary for a deadlock to occur?

o A) Mutual Exclusion

o B) Hold and Wait

o C) Preemption

o D) Circular Wait

o Answer: C

8. In a system with 3 processes and 2 resources, if each process holds 1 resource and is waiting
for 1 more resource, what is the system experiencing?
 o A) Starvation

o B) Deadlock

o C) Thrashing

o D) None of the above

o Answer: B

9. What is a deadlock avoidance strategy?

o A) Ignoring the problem and hoping it resolves itself

o B) Allowing deadlocks to happen and recovering from them later

o C) Ensuring that at least one of the necessary conditions for deadlock cannot hold

o D) Terminating processes randomly to free up resources

o Answer: C

10. Which algorithm is used to avoid deadlocks by ensuring that the system is always in a safe
state?

o A) First-Come, First-Served

o B) Banker's Algorithm

o C) Shortest Job First

o D) Round Robin

o Answer: B

11. If there are 5 processes and 3 resources in a system, how many additional resources must be
available to ensure the system is deadlock-free?

o A) 1

o B) 2

o C) 3

o D) 4

o Answer: B

o Explanation: According to the formula for deadlock avoidance, the number of

additional resources required is (number of processes - 1).