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OS Interview Questions and Answers pdf

OS Interview Questions and Answers pdf

“OS Interview Questions and Answers pdf is given here on this page.”

PrepInsta provides you most common OS Interview Questions and Answers pdf. Technical Interviews are used to check candidates for specialist positions.

OS is one of the common topic asked during Technical Interview.
Interviewer ask questions that will be specific to the role you have applied for, so that he can confirm you have the requisite skills.

Click on the button below to have a detailed look on OS Questions and Answers. Go through the page to know more about OS Interview Questions and Answers pdf.

Top 25 Operating System Interview Questions with Answers

Operating system : Definition

The operating system is the connecting interface between the computer’s hardware and the end user or his actions.

With the aid of computing power and resources offered by the device’s hardware, the operating system executes functions required by the end user or enabling tasks to deliver features to the end user.

Frequently Asked OS Interview Questions and Answers pdf

1. What is an operating system?

Solution:-

The operating system is a software program that facilitates computer hardware to communicate and operate with the software applications and it acts as an interface between the user and the computer hardware. It is the most important part of a computer system without it computer is just like a box.

2. What is deadlock? 

Solution:-

Deadlock is a situation when two or more processes wait for each other to finish and none of them ever finish. Consider an example when two trains are coming toward each other on same track and there is only one track, none of the trains can move once they are in front of each other. Similar situation occurs in operating systems when there are two or more processes hold some resources and wait for resources held by other(s).

3. What is time- sharing system?

Solution:-

In a Time-sharing system, the CPU executes multiple jobs by switching among them, also known as multitasking. This process happens so fast that users can interact with each program while it is running.

4. Which of the following is the number of processes that complete their execution per time unit?

a. Throughput    

b. Turnaround time  

c. Waiting time    

d. Response time

Solution:-

a. Throughput

Throughput – number of processes that complete their execution per time unit. Turnaround time – amount of time to execute a particular process. Waiting time – amount of time a process has been waiting in the ready queue. Response time – amount of time it takes from when a request was submitted until the first response is produced, not output (for time-sharing environment).

5. What are the functions of operating system?

 Solution:-

The operating system controls and coordinates the use of hardware among the different processes and applications. It provides the various functionalities to the users. The following are the main job of operating system.

– Resource utilization
– Resource allocation
– Process management
– Memory management
– File management
– I/O management
– Device management

 6.What Are Real-time Systems?

Solution:-

Real-time systems are used when rigid time requirements have been placed on the operation of a processor. It has well defined and fixed time constraints.

7. Explain the concept of Reentrancy?

Solution:-

It is a useful, memory-saving technique for multiprogrammed timesharing systems. A Reentrant Procedure is one in which multiple users can share a single copy of a program during the same period. Reentrancy has 2 key aspects: The program code cannot modify itself, and the local data for each user process must be stored separately. Thus, the permanent part is the code, and the temporary part is the pointer back to the calling program and local variables used by that program. Each execution instance is called activation. It executes the code in the permanent part, but has its own copy of local variables/parameters. The temporary part associated with each activation is the activation record. Generally, the activation record is kept on the stack.
Note: A reentrant procedure can be interrupted and called by an interrupting program, and still execute correctly on returning to the procedure.

8. What is multi-programming, and what are the advantages?

Solution:-

A multiprogramming operating system is one that allows a process where multiple programs execute over one CPU. If your interviewer asks OS questions on multiprogramming, you can highlight key differences between a multiprogramming OS and other systems.

One way to display that you understand the benefits of multi-programming is to use a real-life example. By offering an instance when you used multi-programming to receive such benefits, you are displaying hands-on knowledge of a system that might be important to the interviewer.

9. What is virtual memory?

Solution:-

Virtual memory is a memory management method that helps to execute the process using the primary and secondary memory. Though the program gets executed using the main memory, the resources and pages load from the secondary memory.

10. What is Thrashing?

Solution:-

Thrashing is a situation when the performance of a computer degrades or collapses. Thrashing occurs when a system spends more time processing page faults than executing transactions. While processing page faults is necessary to in order to appreciate the benefits of virtual memory, thrashing has a negative affect on the system. As the page fault rate increases, more transactions need processing from the paging device. The queue at the paging device increases, resulting in increased service time for a page fault.

 

11. What is the difference between micro kernel and macro kernel?

Solution:-

Micro kernel: micro kernel is the kernel which runs minimal performance affecting services for operating system. In micro kernel operating system all other operations are performed by processor.

Macro Kernel: Macro Kernel is a combination of micro and monolithic kernel.

12. Enumerate the different RAID levels.

Solution:-

RAID 0 – Non-redundant striping
RAID 1 – Mirrored Disks
RAID 2 – Memory-style error-correcting codes
RAID 3 – Bit-interleaved Parity
RAID 4 – Block-interleaved Parity
RAID 5 – Block-interleaved distributed Parity
RAID 6 – P+Q Redundancy

13. Is it possible to have a deadlock involving only one process? Explain your answer.

Solution:-

Deadlock with one process is not possible. Here is the explanation.

A deadlock situation can arise if the following four conditions hold simultaneously in a system.

  • Mutual Exclusion.
  • Hold and Wait.
  • No Preemption.
  • Circular-wait.

It is not possible to have circular wait with only one process, thus failing a necessary condition for Circular wait. There is no second process to form a circle with the first one. So it is not possible to have a deadlock involving only one process.

14. How Are Server Systems Classified?

Solution:-

Server systems can be classified as either computer-server systems or file server systems. In the first case, an interface is made available for clients to send requests to perform an action. In the second case, provisions are available for clients to create, access and update files.

15. List the Coffman’s conditions that lead to a deadlock.

Solution:-

  1. Mutual Exclusion: Only one process may use a critical resource at a time.
  2. Hold & Wait: A process may be allocated some resources while waiting for others.
  3. No Pre-emption: No resource can be forcible removed from a process holding it.
  4. Circular Wait: A closed chain of processes exist such that each process holds at least one resource needed by another process in the chain.

16. Describe how to boot an operating system.

Solution:-

The word “boot” is short for “bootstrap,” which is the name of the program that prompts the operating system at startup. Booting occurs when you start a computer from the kernel. This usually happens when you start it for the first time. It may also occur when the computer malfunctions and you have to put it in safe mode or reboot it as though it were a new CPU.

Booting an operating system is an essential function that applies to many varied work environments. If you have a workplace with computers, it’s highly likely you will have to boot new and existing computers as an IT professional. The answer to this question offers the interviewer a read on your fundamental skills with regards to operating systems.

17.What is demanding Paging?

Solution:-

Demanding pages is a concept used by the virtual machine. Only a part of the process needs to be present in the main memory to execute some process, which means that only a few pages will only be present in the main memory at any time, and rest will be kept in the secondary memory.

18. What is Banker’s algorithm?

Solution:-

Banker’s algorithm is used to avoid deadlock. It is the one of deadlock-avoidance method. It is named as Banker’s algorithm on the banking system where bank never allocates available cash in such a manner that it can no longer satisfy the requirements of all of its customers.

19.  Give an example of a Process State.

Solution:-

  • New State – means a process is being created
  • Running – means instructions are being executed
  • Waiting – means a process is waiting for certain conditions or events to occur
  • Ready – means a process is waiting for an instruction from the main processor
  • Terminate – means a process is stopped abruptly

20. What is a named pipe?

Solution:-

  • A traditional pipe is unnamed and can be used only for the communication of related process. If unrelated processes are required to communicate – named pipes are required.
  • It is a pipe whose access point is a file available on the file system. When this file is opened for reading, a process is granted access to the reading end of the pipe. Similarly, when the file is opened for writing, the process is granted access to writing end of the pipe.
  • A named pipe is also referred to as FIFO or named FIFO.

21. Explain the main purpose of an operating system?

Solution:-

There are two main purposes of Operating systems :

  • One is that it is designed to make sure a computer system performs well by managing its computational activities.
  • Another is that it provides an environment for the development and execution of programs.

22. What are the advantages of a multiprocessor system?

Solution:-

With an increased number of processors, there is a considerable increase in throughput. It can also save more money because they can share resources. Finally, overall reliability is increased as well.

23. What is kernel?

Solution:-

A kernel is the core of every operating system. It connects applications to the actual processing of data. It also manages all communications between software and hardware components to ensure usability and reliability.

24. What are real-time systems?

Solution:-

Real-time systems are used when rigid time requirements have been placed on the operation of a processor. It has well defined and fixed time constraints.

25. What is time- sharing system?

Solution:-

In a Time-sharing system, the CPU executes multiple jobs by switching among them, also known as multitasking. This process happens so fast that users can interact with each program while it is running.