Operating systems is one of the main subjects for software engineers. because anything that we build is for the operating systems whether it be for Android, IOS, or for Desktop. so here we are including basic to advanced Operating Systems [ os ] Interview Questions and Answers for the preparation of your university exams, competitive exams, for coding contests, or for coding interviews.

Operating Systems [ os ] Interview Questions and Answers

Virtual memory is

  1. an extremely large main memory
  2. an extremely large secondary memory
  3. an illusion of an extremely large memory
  4. a type of memory used in supercomputers

Answer - (3) an illusion of an extremely large memory


Spatial locality refers to the problem that once a location is referenced

  1. it will not be referenced again
  2. it will be referenced again
  3. a nearby location will be referenced soon
  4. none of the above

Answer - (3) a nearby location will be referenced soon


Which of the following is an example of a SPOOLED device?

  1. The terminal is used to enter the input data for a program being executed.
  2. The secondary memory device in a virtual memory system.
  3. A line pinter used to print the O/P of a no. of jobs.
  4. one tries to divide a number by 0.

Answer - (3) A line printer used to print the O/P of a no. of jobs


A page fault occurs when

  1. the page is corrupted by application software
  2. the page is in the main memory
  3. the page is not in the main memory
  4. the tries to divide a number by 0

Answer - (3) the page is not in the main memory


Overlay is

  1. a part of an operating system
  2. a specific memory location
  3. a single contiguous memory that was used in the olden days for running large programs by swapping
  4. overloading the system with many user files

Answer - (3) a single contiguous memory that was used in the olden days for running large programs by swapping


Concurrent processes are processes that

  1. do not overlap in time
  2. overlap in time
  3. are executed by a processor at the same time
  4. none of the above

Answer - (2) overlap in time


The page replacement policy that sometimes leads to more page faults when the size of the memory is increased is

  1. FIFO
  2. LRU
  3. no such policy exists
  4. none of the above

Answer - (1) FIFO


Fragmentation is

  1. dividing the secondary memory into equal-sized fragments
  2. dividing the main memory into equal-size fragments
  3. fragments of memory words used in a page
  4. fragments of memory words unused in a page

Answer - (2) dividing the main memory into equal-size fragments


Which of the following are real-time systems?

An online railway reservation system
A process control system
Aircraft control system
Payroll processing system

  1. 1 and 2
  2. 3 and 4
  3. 2 and 3
  4. 1, 2, 3 and 4

Answer - (3) 2 and 3


Dijkstra's banking algorithms in an operating system solves the problem of

  1. deadlock avoidance
  2. deadlock recovery
  3. mutual exclusion
  4. context switching

Answer - (1) deadlock avoidance


Critical region is

  1. a part of the operating system which is not allowed to be accessed by any process
  2. a set of instructions that access common shared resources which exclude one another in time
  3. the portion of the main memory which can be accessed only by one process at a time
  4. none of these

Answer - (2) a set of instructions that access common shared resources which exclude one another in time


Kernel is

  1. considered as the critical part of the operating system
  2. the software which monitors the operating system
  3. the set of primitive functions upon which the rest of operating system functions are built up
  4. none of the above

Answer - (3) the set of primitive functions upon which the rest of operating system functions are built up


Necessary conditions for deadlock are

  1. non-preemption and circular wait
  2. Mutual exclusion and partial allocation
  3. both (a) and (b)
  4. none of the above

Answer - (3) both (a) and (b)


In a time-sharing operating system. when the time slot given to a process is completed, the process goes from the RUNNING state to the

  1. BLOCKED state
  2. READY state
  3. SUSPENDED state
  4. TERMINATED state

Answer - (2) READY state


At a particular time, the value of a counting semaphore is 10. it will become 7 after

3 V operations
3 P operations
5 V operations and 2 P operations

  1. 1 and 2
  2. 2 and 3
  3. 2 and 4
  4. 4 only

Answer - (3) 2 AND 4


Supervisor call

  1. is a call made by the supervisor of the system
  2. is a call with control functions
  3. are privileged calls that are used to perform resource management functions, which are controlled by the operating system
  4. is a call made by someone working in the root directory

Answer - (3) are privileged calls that are used to perform resource management functions, which are controlled by the operating system


Semaphores are used to solve the problem of

race condition
process synchronization
mutual exclusion

  1. 1 and 2
  2. 2 and 3
  3. All of the above
  4. None of the above

Answer - (2) 2 AND 3


Mutual exclusion problem occurs

  1. between two disjoint processes that do not interact
  2. among processes that share resources
  3. among processes that do not use the same resource
  4. none of the above

Answer - (2) among processes that share resources


Sector interleaving in disks is done by

  1. single-user system
  2. non-multiprogramming system
  3. non-multitasking system
  4. none of these

Answer - (2) non-multiprogramming system


Dirty bit is used to show the

  1. page with corrupted data
  2. wrong page in the memory
  3. the page that is modified after being loaded into the cache memory
  4. a page that is less frequently accessed

Answer - (3) a page that is modified after being loaded into the cache memory

Note - More Interview questions and answers will be added from time to time.