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All OS Interview Questions

Practice the complete collection of OS interview questions including theory, coding, MCQs and real interview problems.

Total Questions: 106Topics: 14Complete interview preparation

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All OS Interview Questions (106)

Scroll through every important OS question asked in real interviews. Includes MCQs, subjective questions, and coding prompts.

1. What is the primary role of an operating system (OS)?

Difficulty: EasyType: MCQTopic: OS Basics

To provide user applications only
To manage hardware and software resources for efficient execution
To replace all application software
To provide only a graphical interface

The operating system acts as the intermediary between hardware and application software. It manages resources like CPU, memory, and I O so applications can run efficiently and correctly.

Correct Answer: To manage hardware and software resources for efficient execution

2. Which of these is a type of operating system?

Difficulty: EasyType: MCQTopic: OS Basics

Batch operating system
Spreadsheet operating system
Database operating system
Office operating system

Operating systems can be classified by how they manage tasks: batch, time-sharing, real-time, etc. A batch operating system schedules jobs without manual intervention.

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All OS Interview Questions

Overview

1. What is the primary role of an operating system (OS)?

2. Which of these is a type of operating system?

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3. What is the role of a kernel in an OS?

4. Explain the difference between a process and a thread.

5. Which of the following is *not* a typical state in a process lifecycle?

6. What is a system call and why is it important?

7. What is multiprogramming in operating systems?

8. Explain what a time-sharing system is.

9. Which of these is *not* an inter-process communication (IPC) mechanism?

10. What is a Process Control Block (PCB) and what information does it store?

11. What is a bootstrap program in an OS context?

12. What is a zombie process and how does it arise?

13. Which statement correctly describes the main difference between a process and a thread?

14. What is a Process Control Block (PCB) and what key information does it hold?

15. Which of the following is *not* typically considered a direct state in the process lifecycle?

16. What are the main goals of CPU scheduling in an operating system?

17. Which scheduling algorithm can lead to starvation of a process if implemented without safeguards?

18. Describe what a context switch is and why minimizing context‐switch time is important.

19. What does multiprogramming in an operating system aim to achieve?

20. Explain the difference between preemptive and non-preemptive CPU scheduling with examples.

21. Which of the following is *not* a classic inter‐process communication (IPC) mechanism?

22. What is the role of the dispatcher in process scheduling?

23. What data structure typically holds processes that are ready to execute on the CPU?

24. In memory management, what is the difference between a logical address and a physical address?

25. Which type of fragmentation occurs when free memory is broken into small pieces and cannot satisfy a process's request even though total free memory is sufficient?

26. Explain contiguous memory allocation and discuss its pros and cons.

27. Which statement about paging in memory management is true?

28. What is segmentation in memory management and how does it differ from paging?

29. Which of these best describes virtual memory?

30. Describe demand paging and how it affects system performance.

31. In the context of page replacement algorithms, which strategy would replace the page that has not been used for the longest time?

32. What is thrashing in memory management and how can it be prevented?

33. Which memory allocation strategy picks the first block that is large enough to satisfy the request?

34. Explain internal and external fragmentation and give examples of each.

35. What is a file system in the context of an operating system?

36. Which file allocation method stores file blocks in links so each block points to the next block?

37. Explain what an inode is in a Unix-style file system and what information it holds.

38. In a hierarchical file system, which directory typically contains configuration files in a Linux system?

39. Describe two common free-space management techniques in file systems and their trade-offs.

40. Why do many modern file systems use journaling?

41. What is an extent-based allocation in a file system and why is it preferred for large files?

42. In a Unix file system, which permission set allows a user to remove files from a directory?

43. What does mounting a file system mean and what role does the mount point play?

44. Which scheduling algorithm attempts to reduce disk arm movement by servicing requests in the direction of the arm until it reaches the end and then reversing?

45. How does the file-system consistency check (fsck) utility work and when is it used?

46. Which of the following is a block device in operating system terms?

47. Explain programmed I O, interrupt-driven I O and direct memory access (DMA).

48. What does spooling in operating systems refer to?

49. What is an interrupt in the context of I O, and how does it differ from polling?

50. Which disk scheduling algorithm treats the disk arm like an elevator, servicing requests in one direction until reaching the end then reversing?

51. What is Direct Memory Access (DMA) and what advantages does it provide over other I O methods?

52. Which statement correctly describes a device driver in an operating system?

53. What is buffering in the context of I O systems? Explain its purpose and trade-offs.

54. How does spooling differ from buffering in I O systems?

55. Differentiate cache versus buffer in the context of I O and memory systems.

56. Which mechanism helps ensure that only authorised processes access I O devices safely in an operating system?

57. What is a deadlock in an operating system?

58. What are the four necessary conditions for a deadlock to occur? Explain each one.

59. Which of these is a common method for detecting deadlock in a system with multiple resource instances?

60. How can an operating system prevent deadlock? Describe at least two techniques with trade-offs.

61. Which of the following is *not* a requirement for a correct solution to the critical-section problem?

62. Explain the difference between a mutex and a semaphore.

63. What does the term ‘aging’ refer to in scheduling/concurrency context?

64. What is the reader-writer problem, and how might an OS handle it? Include considerations for read-heavy vs write-heavy workloads.

65. In a resource allocation graph, what does a cycle indicate if each resource has only one instance?

66. What is a livelock? How is it different from a deadlock? Give an example.

67. Which synchronization primitive ensures both mutual exclusion and prevents data race in a multithreaded program?

68. Which access control model enforces that subjects cannot read up and cannot write down, typically used in high-security systems?

69. Explain the difference between kernel mode and user mode in an operating system and why the distinction matters for security.

70. Which principle states that a process or user should be given no more access than necessary to perform its job?

71. What is the W^X (Write XOR Execute) policy in operating systems and how does it enhance security?

72. What is the purpose of kernel patch protection (KPP) as implemented in some operating systems?

73. What is a rootkit and how can operating system design help defend against it?

74. Which term describes a secure area of a main processor that provides isolated execution for code and data, even from higher-privileged code on the system?

75. Why is the Principle of Least Common Privilege important in operating system security and how would you implement it in OS design?

76. What does secure boot in modern operating systems ensure?

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5. Which of the following is not a typical state in a process lifecycle?

9. Which of these is not an inter-process communication (IPC) mechanism?

15. Which of the following is not typically considered a direct state in the process lifecycle?

21. Which of the following is not a classic inter‐process communication (IPC) mechanism?

61. Which of the following is not a requirement for a correct solution to the critical-section problem?