Top Operating System Interview Questions and Answers

Here are top OS interview questions,

1. What is an operating system?

An operating system is software that manages computer hardware and software resources, providing services for user programs and acting as an intermediary between applications and the hardware.

 

2. What are the main functions of an operating system?

The main functions of an operating system include process management, memory management, file system management, device management, and user interface management.

 

3. What are the main types of operating systems?

The main types of operating systems are:

·       Desktop Operating Systems (e.g., Windows, macOS, Linux)

·       Mobile Operating Systems (e.g., Android, iOS)

·       Server Operating Systems (e.g., Windows Server, Linux Server)

·       Real-time Operating Systems (RTOS) for time-sensitive applications

·       Embedded Operating Systems (ETOS) for embedded systems and devices.

 

4. What is virtual memory, and how does it work?

Virtual memory is a memory management technique that allows the execution of processes that are not entirely in physical memory. It uses a combination of RAM and disk space to simulate more memory than is physically available.

 

5. What is a deadlock, and how can it be prevented?

A deadlock is a situation where two or more processes are unable to proceed because each is waiting for the other to release a resource. Deadlocks can be prevented using various methods, such as deadlock avoidance algorithms or resource allocation strategies like Banker's algorithm.

 

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

A process is an independent program with its own memory space, whereas a thread is a smaller unit of a process that shares the same memory space with other threads in the same process.

 

7. What is a kernel?

The kernel is the core component of an operating system, responsible for managing memory, processes, and I/O operations. It directly interacts with the hardware and provides essential services for other parts of the operating system and applications.

 

8. What is the role of the shell in an operating system?

The shell is a command-line interface that allows users to interact with the operating system. It interprets user commands and executes them by calling the appropriate system functions.

 

9. Explain the difference between a monolithic kernel and a microkernel.

A monolithic kernel has most of the operating system functions within the kernel space, while a microkernel keeps only essential functions in the kernel space and moves non-essential ones to user space as separate processes or servers.

 

10. What is a page fault?

A page fault occurs when a program references a page of memory that is not currently in RAM but resides in secondary storage (like a hard disk). The operating system then fetches the required page into RAM to continue execution.

 

11. What is thrashing, and how can it be avoided?

Thrashing is a situation where the system spends more time swapping data between RAM and disk than executing useful tasks. It can be avoided by increasing the amount of RAM, improving memory management algorithms, or reducing the number of processes running concurrently.

 

12. Explain the concept of a context switch.

A context switch is the process of saving the state of a running process and loading the state of a new process so that execution can continue without interruption. It allows the operating system to switch between processes efficiently.

 

13. What is a semaphore, and how is it used for process synchronization?

A semaphore is a synchronization mechanism used to control access to shared resources in a multi-process or multi-threaded environment. It acts as a counter to limit the number of processes or threads that can access a shared resource simultaneously.

 

14. What are device drivers, and why are they important?

Device drivers are software components that allow the operating system to communicate with hardware devices. They are crucial because they enable the operating system to manage and control various hardware peripherals effectively.

 

15. What is a file system?

A file system is a method used by the operating system to organize and store files on storage devices. It provides a logical structure that allows users and applications to access and manage files efficiently.

 

16. How does a fork() system call work?

The fork() system call creates a new process (child) that is an exact copy of the calling process (parent). Both processes continue execution from the point of the fork() call, but they have separate memory spaces.

 

17. Explain the difference between multi-tasking and multi-threading.

Multi-tasking allows multiple processes to run concurrently on a single processor, while multi-threading enables multiple threads within a process to execute concurrently.

 

18. What is the booting process, and what happens during each boot phase?

Booting is the process of starting up a computer. During each boot phase, the hardware initializes, the BIOS/UEFI loads the bootloader, the bootloader loads the operating system kernel, and finally, the operating system starts executing and initializes user space.

 

19. How does the priority-based scheduling algorithm work in an operating system?

In priority-based scheduling, each process is assigned a priority, and the CPU is allocated to the process with the highest priority. Preemptive priority scheduling allows a higher priority process to interrupt a lower priority process currently running.

 

20. What is a watchdog timer, and how is it used in an embedded system?

A watchdog timer is a hardware or software mechanism used to monitor the proper functioning of a system. It needs to be periodically reset by the operating system, and if the system hangs or fails to reset the timer, the watchdog triggers a system reset to recover from the failure.

 

Above are few top OS interview questions. Remember to prepare and expand on these answers.

Good luck with your interview!  👍