15 Operating System Interview Questions and Answers

Operating systems are greatly being used today in computers and other related devices. Therefore, there has been an increase in job demand for their design, maintenance, and repair. Due to that rising demand, we have decided to compile 15 operating system interview questions and how to answer them. This tutorial is aimed at equipping you with the knowledge on the type of issues to expect when attending your operating system interview. The operating system interview questions are discussed intensely to ensure that you have authority over the subject.

Question 1: What’s an Operating System?

An operating system is a program forming a bridging interface between the user and the computer hardware. It provides users with a suitable environment through which they can interact with the computer components.

Question 2: What Roles Does an Operating System Play?

  • An operating system coordinates and controls how the various applications within the system use the computer hardware components.
  • It also manages and allocates resources such as space and time. In addition to that, it schedules the various tasks within the computer depending on the urgency of each particular task.
  • It forms an integral part of the error handling system.
  • It controls how the input and output devices operate.

Question 3: Which Are the Different Types of Operating Systems?

This is rather common when dealing with frequently asked operating system interview questions. It seeks to establish whether you know the various types based on their areas of application. The different types are:

  • Multi-programmed operating systems;
  • Batched operating systems;
  • Distributed operating systems;
  • Real-time operating systems;
  • Time-sharing operating systems.

Question 4: What Do the Terms Process and Process Table Mean?

A process is a program in execution. Usually, there are operating system processes and user processes. The operating system monitors all the process. Depending on the priority, it allocates time to each of them as to when they should be executed by the processor. Therefore, it needs to maintain all of the schedules in an organized table referred to as the process table. This way the OS keeps track of all the processes, the resources they are using and the state of each process.

Question 5: What Are the Different States of a Process?

Processes have three different states: running, ready, or waiting.

In the running state, the process has acquired all the resources it needs and has been green-lighted by the OS to use the processor.

In the ready and waiting states, the processes are in a queue because only one process can be running at an instance. For example, a program may be in waiting when it requires an external resource or action such as input or a storage device access. The ready state may mean that the process is waiting for the processor to finish with the running program or permission from OS.

Question 6: What Is a Thread?

A thread is the smallest programmed sequence of instructions that can be executed independently within a process. They may have similar properties to processes hence referred to as lightweight processes. Threads are responsible for parallelism used in most operating systems to run different tasks simultaneously. They have personal program counters, register sets and stack space. Unlike processes, they are dependent on one another and may share code section, data section, and other OS resources.

Question 7: What is Reentrancy?

This is one of the trickiest operating system interview questions you culd receive. Reentrancy is an important technique for saving memory in multi-programmed timesharing systems. When a procedure is deemed reentrant, it means that the several users can share an individual copy of the program at an instance. This process is achieved through a permanent code execution and a temporary pointer which invokes a copy of local programs and variables.

Question 8: What Is a Kernel?

This is the central part of an operating system. It facilitates the communication between hardware and software components. In addition to that, it acts as a bridge between the applications and the actual data processing in the system.

Question 9: Why Are Multiprocessor Systems Preferred?

The increase in processor number within a system increases the overall throughput. It is also economical since resources are easily shared. They have also proved to be reliable based on their improved performance.

Question 10: What Is the Difference between Real Time and Time Sharing Systems?

Real-time systems are applicable in scenarios when the processor is scheduled to operate on rigid time requirements. These types of systems have well defined time restrictions.

Time sharing systems, on the other hand, involve the central processing unit performing multiple tasks by swapping between them. The process is commonly referred to as multi-tasking. It takes place in fractions of seconds to the point that users can interact with the running programs at the same time.

Recommended read: If you’re interested in other collections of questions and answers that might help while interviewing for IT jobs, also check out our Apache interview questions

Question 11: How Can One Classify the Server Systems?

This question is one of the most self-explanatory and intuitive operating system interview questions. Server systems are categorized in two; computer server systems and file server systems. In the former, clients are offered with an interface through which they can send their requests and action demands. The latter allows users to create, access, or update files.

Question 12: What Is a Deadlock, and what Are Its Possible Causes?

A deadlock is a situation where two processes are waiting for each other to terminate so they can start. The conditions under which this occurs are:

  • Mutual exclusion: this is when the resource needed by the two processes cannot be shared.
  • Hold and wait: when a process is holding a particular resource while waiting for another resource. However, the resource being waited on may be in use with another process.
  • No preemption: It occurs when the OS cannot reclaim a resource from a process unless it yields back the resource.
  • Circular wait: this is when a series of processes are waiting on each other in one circular sequence.

Question 13: What Is Virtual Memory?

This is a condition whereby an illusion is created that each user has one or multiple adjoining address spaces starting at address zero. It plays a role in extending the RAM space by the use of disk space to complement the RAM. The virtual addresses are characteristically large and can, therefore, be subdivided into smaller pieces. The resultant pieces are then called upon by the physical memory each time they are needed.

Question 14: What Are Overlays in Operating Systems?

Overlays are used to make a given process larger than its allocated space by the OS. This is important in the sense that only the needed data and instructions at a particular time are sifted out.

Question 15: What Is Demand Paging?

This is when just some processes or none are in the RAM. Hence, the OS calls the missing processes, which are needed, from the disk to the physical memory. It is an important method of virtual memory management.

Its opposite is the anticipatory paging. It predicts the pages that may be needed for referencing shortly by a given task.


After reading these 15 basic operating system interview questions above, we believe you are now ready for your interview. Note that these questions can be framed differently as much as the concept is still the same. Therefore, you can comb the web for more information (though we’ve compiled the best ones for you here) and feel free to share with us. You will naturally find these concepts applicable even after getting the job.