▷ Operating System MCQs (Multiple Choice Questions)

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

2. Which component of an OS provides abstractions like files, processes and sockets?

3. Which OS type runs on top of another host OS as a process?

4. Which term describes the ability to run multiple programs seemingly simultaneously?

5. What is a context switch?

6. Which of the following is NOT a type of OS kernel?

7. Which OS allows direct access to hardware from user programs?

8. Which mode provides full access to CPU instructions and hardware in most systems?

9. What is a system call?

10. Which resource is typically NOT managed by the OS?

11. What is the difference between a process and a thread?

12. Which operation creates a new process in UNIX-like systems?

13. Which thread model maps many user-level threads to one kernel thread?

14. Which mechanism allows a process to wait for another process to finish?

15. Which state indicates a process is ready to run but not currently running?

16. What is inter-process communication (IPC)?

17. Which IPC method provides the fastest data sharing between processes on the same machine?

18. What is a zombie process?

19. Which scheduling type gives each runnable process a fixed time slice cyclically?

20. Which scheduling metric measures average time from job submission to completion?

21. Which scheduling algorithm can suffer from starvation?

22. Which term describes the number of processes completed per unit time?

23. Which scheduling algorithm minimizes average waiting time when jobs arrive simultaneously and durations are known?

24. What is preemption?

25. What is dispatch latency?

26. What is virtual memory?

27. Which is a benefit of paging over contiguous allocation?

28. What maps virtual addresses to physical addresses in paging?

29. What is page fault?

30. What is TLB (Translation Lookaside Buffer) used for?

31. Which replacement policy is optimal but impractical because it requires future knowledge?

32. What problem can occur when the working set of processes exceeds physical memory?

33. Which technique reduces internal fragmentation by using variable-sized segments?

34. Which memory allocation results in external fragmentation?

35. Which problem does mutual exclusion solve?

36. Which primitive can be used to provide mutual exclusion?

37. Which scenario describes deadlock?

38. Which condition is NOT one of Coffman’s necessary conditions for deadlock?

39. Which is a method to handle deadlocks by ensuring they never occur?

40. Which algorithm is used for deadlock avoidance by checking safe states?

41. What is an inode (in UNIX-like file systems)?

42. Which technique reduces file system fragmentation by keeping blocks contiguous?

43. Which file system feature protects against corruption during crashes by recording intended changes before applying them?

44. Which RAID level mirrors data across disks for redundancy?

45. Which operation translates a pathname to an inode?

46. Which layer translates generic I/O requests into device-specific operations?

47. Which I/O technique allows CPU to do other work while device transfers data and interrupt when done?

48. What is spooling?

49. Which queueing discipline ensures fairness by serving the shortest remaining service time?

50. In buffered I/O, which benefit is true?

51. What is the hypervisor's primary job?

52. Which type of virtualization shares the host OS kernel across containers?

53. Which technique reduces attack surface by running services with least privileges?

54. Which vulnerability involves writing past the end of a buffer?

55. Which mechanism isolates processes and enforces memory protection?

56. What is kernel preemption useful for in modern OSes?

57. What is a race condition?

58. Which strategy improves throughput by executing independent instructions from multiple threads out-of-order?

59. Which structure stores a process's CPU registers, program counter and stack pointer during context switch?

60. Which scheduling is best for interactive systems to ensure low response time?

61. Which design aids portability across hardware architectures?

62. Which utility analyzes and repairs inconsistent filesystem metadata after a crash?

63. Which scheduling technique is often used by kernels to reduce lock contention by letting threads run on the same CPU core repeatedly?

64. Which logging mechanism in OSes is commonly used for auditing and diagnosing kernel events?

65. What is a suspend-to-disk (hibernate) operation?

66. Which mechanism can be used to limit resource usage (CPU, memory) per process on UNIX-like systems?

67. What is the purpose of kernel modules?

68. Which technique can improve filesystem reliability by writing operations in a way that can be rolled back if interrupted?

69. What is the benefit of copy-on-write (COW) for forked processes?

70. Which testing practice is critical when changing kernel or driver code?

71. Which Linux subsystem is responsible for enforcing security policies like SELinux?

72. What is cgroups primarily used for?

73. Which filesystem uses copy-on-write by design?

74. What is eBPF mainly used for in modern Linux systems?

75. Which component manages containers in Kubernetes nodes?

76. What is the advantage of NVMe over traditional SATA SSDs?

77. Which security model assumes no implicit trust inside or outside network boundaries?

78. Which Linux command shows kernel ring buffer messages?

79. What is the primary benefit of microkernel architecture?

80. Which feature improves isolation between containers?

81. Which mechanism isolates processes by providing separate views of system resources in Linux?

82. What is the primary goal of load balancing in distributed systems?

83. Which Linux feature allows dynamic tracing of system calls without modifying kernel source?

84. Which scheduler in Linux is commonly used for fair CPU distribution?

85. Which OS concept ensures data consistency across distributed nodes?

86. Which filesystem is widely used in Linux distributions by default?

87. What is the role of systemd in Linux?

88. Which concept improves fault tolerance in distributed systems?

89. Which OS mechanism allows hot-plugging of devices?

90. Which architecture style is common in cloud-native operating systems?

91. Which OS feature helps prevent privilege escalation?

92. Which Linux command monitors real-time process activity?

93. Which approach improves high availability in production systems?

94. What is observability in operating systems?

95. Which kernel feature helps mitigate speculative execution vulnerabilities?

96. Which storage solution is common in distributed cloud environments?

97. Which OS feature isolates applications using lightweight virtualization?

98. Which tool is commonly used for performance profiling in Linux?

99. Which OS mechanism supports sandboxing of applications?

100. Which design principle improves OS scalability?

101. Which modern trend is shaping next-generation operating systems?

102. Which scheduling algorithm always selects the process with the shortest remaining execution time?

103. Which memory management technique divides memory into fixed-size blocks?

104. Which disk scheduling algorithm services requests in the order they arrive?

105. Which IPC mechanism uses a temporary communication channel between processes?

106. Which state follows the Running state when a process requests I/O?

107. Which technique combines segmentation and paging?

108. Which file allocation method stores all file blocks consecutively?

109. Which deadlock prevention strategy eliminates the hold-and-wait condition?

110. Which scheduling algorithm is non-preemptive by default?

111. What is the primary purpose of a bootloader?

112. Which synchronization primitive maintains a counter to control access?

113. Which disk scheduling algorithm moves the disk arm in one direction and then reverses?

114. What is the primary goal of memory protection?

115. Which command in Linux displays currently running processes?

116. Which layer of the OS interacts directly with hardware?

117. Which memory allocation strategy chooses the smallest available partition?

118. Which Linux command displays memory usage statistics?

119. Which mechanism allows a process to communicate with another process over a network?

120. Which operating system component is responsible for allocating CPU time to processes?

121. What is the primary purpose of a system call interface?

122. Which process state indicates that a process is waiting for an event such as I/O completion?

123. Which scheduling algorithm selects the process with the smallest estimated CPU burst?

124. What is starvation in process scheduling?

125. Which technique can prevent starvation in priority scheduling?

126. What is the main function of the Memory Management Unit (MMU)?

127. Which page replacement algorithm removes the page that has not been used for the longest time?

128. What is Belady's anomaly?

129. Which page replacement algorithm is commonly associated with Belady's anomaly?

130. What does demand paging mean?

131. Which synchronization problem involves multiple processes competing to access shared data simultaneously?

132. What is a spinlock?

133. Which classic synchronization problem demonstrates coordination between processes that share a fixed-size buffer?

134. Which deadlock condition states that a resource cannot be forcibly taken away from a process?

135. What does a safe state mean in deadlock avoidance?

136. Which file allocation method stores pointers to all of a file's data blocks in a separate index block?

137. What is the main difference between a hard link and a symbolic link in UNIX-like systems?

138. Which disk scheduling algorithm selects the pending request closest to the current disk head position?

139. What is memory-mapped I/O?

140. What is an interrupt handler?

141. Which type of hypervisor runs directly on physical hardware?

142. Which Linux mechanism restricts the system calls a process is allowed to execute?

143. What is Address Space Layout Randomization (ASLR) designed to do?

144. What is NUMA in multiprocessor systems?

145. What is the primary purpose of a real-time operating system (RTOS)?

146. What distinguishes a hard real-time system from a soft real-time system?

147. Which mechanism allows multiple processes to map the same physical memory pages into their address spaces?

148. What is priority inversion?

149. Which technique can help address priority inversion?

150. Which operating system technique allows the kernel to postpone non-critical interrupt processing?

151. Which Linux feature allows multiple isolated environments to share the same kernel?

152. Which scheduling policy is commonly used for real-time tasks requiring deterministic execution?

153. What is the primary advantage of NUMA (Non-Uniform Memory Access) architecture?

154. Which Linux command displays CPU and memory usage of running processes in real time?

155. Which technology enables secure execution of applications inside isolated hardware-protected environments?

156. Which memory management feature delays physical memory allocation until it is actually required?

157. Which operating system component is responsible for resolving DNS queries?

158. Which Linux security feature filters system calls available to an application?

159. Which page replacement algorithm approximates LRU while requiring less overhead?

160. Which Linux filesystem is specifically optimized for flash storage devices?

161. Which hardware feature helps accelerate virtual machines by reducing virtualization overhead?

162. Which Linux command displays disk space usage of mounted file systems?

163. Which feature allows snapshots to be created instantly without copying all existing data?

164. Which Linux command displays active network connections and listening ports?

165. Which operating system concept allows software updates without rebooting the entire system?

166. Which Linux kernel feature enables high-performance asynchronous I/O introduced as a replacement for traditional AIO?

167. Which Linux mechanism isolates CPU, memory, and I/O resources for containers?

168. Which scheduling strategy is increasingly used in cloud environments to optimize workload placement?

169. Which technology allows a VM to migrate from one physical host to another with minimal downtime?

170. Which Linux command displays detailed information about block storage devices?

171. Which Linux utility is commonly used to monitor system performance and collect performance statistics?

172. Which filesystem is designed to provide scalability for enterprise workloads and very large storage systems?

173. Which kernel feature helps detect and prevent stack-based memory corruption attacks?

174. Which Linux command displays CPU architecture and kernel version information?

175. Which technique allows an operating system to randomize memory addresses to improve security?

176. Which operating system concept enables applications to recover automatically after node failures in a cluster?

177. Which virtualization technology allows multiple operating systems to run on the same hardware with near-native performance?

178. Which Linux mechanism notifies applications about file or directory changes?

179. Which emerging trend uses machine learning to optimize resource allocation and workload scheduling in operating systems?

180. Which operating system trend is becoming increasingly important for edge computing and IoT deployments?

181. Which Linux feature allows applications to communicate directly with high-speed storage devices while reducing kernel overhead?

182. Which Linux security module provides mandatory access control using security policies?

183. Which feature enables applications running in containers to communicate securely using encrypted service meshes?

184. Which Linux command is commonly used to display memory usage statistics?

185. Which scheduling approach is widely used in Kubernetes for assigning Pods to nodes?

186. Which operating system feature allows memory pages to be compressed instead of immediately swapping them to disk?

187. Which Linux feature enables live tracing of kernel and application performance with minimal overhead?

188. Which virtualization technology allows multiple isolated kernels to run on the same hardware?

189. Which Linux command is commonly used to monitor real-time disk I/O statistics?

190. Which technology enables confidential virtual machines by protecting data while it is being processed?

191. Which Linux utility displays process hierarchy in a tree-like format?

192. Which operating system concept helps improve application resilience by automatically restarting failed services?

193. Which Linux feature isolates network interfaces between containers?

194. Which scheduling metric measures the time from a request being submitted until the first response is produced?

195. Which file system is developed by Microsoft and is optimized for flash drives and SD cards?

196. Which emerging operating system trend focuses on running workloads closer to data sources to reduce latency?

197. Which Linux feature ensures that only verified kernels and bootloaders are loaded during system startup?

198. Which kernel mechanism is responsible for handling hardware-generated events?

199. Which modern OS capability enables predictive scaling of system resources using historical workload patterns?

200. Which operating system trend is expected to play a major role in cloud-native infrastructure over the next few years?