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Operating System Interview Questions

Check the list of Operating System interview questions covering various topics like definitions, memory management, processes, file systems, scheduling algorithms, and advanced concepts, which will help you prepare well for interviews. This will be useful for both beginners and experienced professionals.

What is an Operating System?

An Operating System (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. It acts as an intermediary between users and the computer hardware.

Why Operating System is Important from a Placements Perspective

Having a strong understanding of Operating System concepts is crucial for technical interviews, particularly for roles related to system-level programming, software engineering, and IT infrastructure. Here's why it should be a priority for you:

Core Knowledge: Operating systems are fundamental to understanding how computer systems function, and many technical interviews test your knowledge of OS concepts.
Real-World Relevance: OS knowledge is crucial in handling memory, processes, and scheduling in real-world applications and server environments.
Performance Tuning: An understanding of OS concepts helps in optimizing system performance, especially for backend or embedded systems roles.
Problem-Solving Skills: OS interview questions often involve problem-solving in areas like resource allocation, synchronization, and deadlock handling, showcasing your analytical skills.
Industry Demand: Professionals who are proficient in OS concepts, especially in areas like system design and multi-threading, are in high demand across various industries, including tech, embedded systems, and telecommunications.

1. Basic Concepts

What is an operating system?
What are the main functions of an operating system?
Explain the difference between monolithic and microkernel architectures.
What is a kernel?
What is the difference between user mode and kernel mode?
What is IPC? What are the different IPC mechanisms?
What's the main purpose of an OS? What are the different types of OS?
What are the benefits of a multiprocessor system?
What is RAID structure in OS? What are the different levels of RAID configuration?
What is GUI?
What is a Pipe and when is it used?
What are the different kinds of operations that are possible on semaphore?
What is a bootstrap program in OS?
Explain demand paging.
What do you mean by RTOS?
What do you mean by process synchronization?
Why is the operating system important?
What is the difference between main memory and secondary memory?
What do you mean by overlays in OS?
Write top 10 examples of OS.
What is multitasking?
What is caching?
What is spooling?
What is the functionality of an Assembler?
What are interrupts?
What is preemptive multitasking?
What is a zombie process?
What are orphan processes?
What is starvation and aging in OS?
What is a dispatcher?
Define the term dispatch latency.
What are the goals of CPU scheduling?
What is a critical section?
Write the name of synchronization techniques.
What is Peterson’s approach?
Define the term Bounded waiting.
What are the solutions to the critical section problem?
What is a Banker’s algorithm?
What is concurrency?
Write a drawback of concurrency.
What are the necessary conditions which can lead to a deadlock in a system?
What are the issues related to concurrency?
Why do we use precedence graphs?
Explain the resource allocation graph.
What is a deadlock?
What is the goal and functionality of memory management?
Write the difference between physical address and logical address.
Explain address binding.
Write different types of address binding.
Write an advantage of dynamic allocation algorithms.
Define Compaction.
Write about the advantages and disadvantages of a hashed-page table.
Write the difference between paging and segmentation.
Write a definition of Associative Memory and Cache Memory.
What is “Locality of reference”?
Write down the advantages of virtual memory.
How to calculate performance in virtual memory?
Write down the basic concept of the file system.
Write the names of different operations on a file.
Define the term Bit-Vector.
What is a File allocation table?
What is rotational latency?
What is seek time?
What is Belady’s Anomaly?
What happens if a non-recursive mutex is locked more than once?
What are the advantages of a multiprocessor system?
What are real-time systems?
How to recover from a deadlock?
What factors determine whether a detection algorithm must be utilized in a deadlock avoidance system?

2. Process Management

What is a process?
What is a process and process table?
What are the different states of a process?
Explain the states of a process (e.g., new, ready, running, waiting, terminated).
What is a Process Control Block (PCB)?
What is context switching?
What is the difference between a process and a thread?
What is a Thread?
What are the differences between process and thread?
What are the benefits of multithreaded programming?
What is multithreading?
Explain the concept of process scheduling.
What are the different types of schedulers (long-term, short-term, medium-term)?
What is the difference between preemptive and non-preemptive scheduling?
Explain common scheduling algorithms (FCFS, SJF, Round Robin, Priority Scheduling).
What is FCFS?
What is the RR scheduling algorithm?
What is Reentrancy?
What is a Scheduling Algorithm? Name different types of scheduling algorithms.
What is cascading termination?

3## 3. Memory Management

What is memory management?
Explain the concept of paging.
What is segmentation?
What is virtual memory?
Explain the difference between internal and external fragmentation.
What is a page fault?
What is a page replacement algorithm? Explain FIFO, LRU, and Optimal algorithms.
What is thrashing?
What is fragmentation?
What is the basic function of paging?
How does swapping result in better memory management?
What is the best page size when designing an operating system?

4. File Systems

What is a file system?
Explain the difference between FAT, NTFS, and ext4 file systems.
What is a directory structure?
Explain the concept of inodes in Unix-based systems.
What is RAID? Explain different RAID levels.
What is a journaling file system? How does it improve reliability?
What is the difference between hard links and symbolic links?
What is file fragmentation, and how does it affect performance?
What is a file descriptor? How is it used in file operations?
What is the purpose of the open(), read(), write(), and close() system calls?
What is a mount point in a file system?
What is the difference between a block device and a character device?
What is the purpose of the fsck utility in Unix-based systems?
What is a distributed file system? Give examples.
What is the role of the File Allocation Table (FAT) in the FAT file system?
What is the difference between a file system and a database system?

5. Deadlocks

What is a deadlock?
Explain the four necessary conditions for a deadlock (mutual exclusion, hold and wait, no preemption, circular wait).
What are the strategies for handling deadlocks (prevention, avoidance, detection, and recovery)?
Explain the Banker's Algorithm for deadlock avoidance.
What is a resource allocation graph? How is it used to detect deadlocks?
What is the difference between deadlock prevention and deadlock avoidance?
What is the Ostrich Algorithm in deadlock handling?
What is livelock, and how is it different from deadlock?
What is the difference between deadlock and starvation?
How can timeouts be used to handle deadlocks?
What is the role of the wait-die and wound-wait schemes in deadlock prevention?
What is a safe state in the context of deadlock avoidance?
What is the difference between a single-instance and multi-instance resource system in deadlock handling?

6. Inter-Process Communication (IPC)

What is IPC?
Explain different IPC mechanisms (pipes, message queues, shared memory, sockets).
What is a semaphore?
Explain the difference between a mutex and a semaphore.
What is a race condition?
What are the advantages of semaphores?
What are the drawbacks of semaphores?
What is a named pipe (FIFO)? How is it different from an unnamed pipe?
What is the difference between synchronous and asynchronous IPC?
What is a message queue, and how does it work?
What is shared memory, and how is it implemented?
What is the difference between blocking and non-blocking IPC?
What is a condition variable, and how is it used in IPC?
What is the producer-consumer problem, and how can IPC mechanisms solve it?
What is the difference between direct and indirect communication in IPC?
What is the role of signals in IPC?
What is a socket, and how is it used for network communication?

7. Storage Management

What is disk scheduling?
Explain common disk scheduling algorithms (FCFS, SSTF, SCAN, C-SCAN, LOOK, C-LOOK).
What is the difference between sequential and random access?
Explain the concept of disk partitioning.
What is the purpose of the Master Boot Record (MBR)?
What is the difference between primary and extended partitions?
What is the role of the disk controller in storage management?
What is the difference between logical and physical formatting of a disk?
What is the purpose of bad block management in storage systems?
What is the difference between RAID 0, RAID 1, RAID 5, and RAID 10?
What is the purpose of caching in storage systems?
What is the difference between hot-swappable and non-hot-swappable storage devices?
What is the role of the swap space in memory management?
What is the difference between a solid-state drive (SSD) and a hard disk drive (HDD)?

8. Security and Protection

What is the difference between authentication and authorization?
Explain the concept of access control lists (ACLs).
What is a buffer overflow?
What is a rootkit?
Explain the principle of least privilege.
What is the difference between symmetric and asymmetric encryption?
What is a firewall, and how does it enhance system security?
What is the role of a security kernel in an operating system?
What is the difference between a virus, worm, and Trojan horse?
What is the purpose of a sandbox in system security?
What is the difference between discretionary access control (DAC) and mandatory access control (MAC)?
What is the role of a security token in authentication?
What is the difference between intrusion detection and intrusion prevention systems?
What is the purpose of encryption in file systems?
What is the difference between a vulnerability and an exploit?

9. Advanced Topics

What is a real-time operating system (RTOS)?
Explain the concept of virtualization.
What is a hypervisor?
What is containerization? How is it different from virtualization?
Explain the concept of distributed operating systems.
What are different types of Kernel?
What do you mean by Semaphore in OS? Why is it used?
What is Kernel and write its main functions?
Write the difference between microkernel and monolithic kernel.
What is SMP (Symmetric Multiprocessing)?
What is a time-sharing system?
What is the difference between Kernel and OS?
What are various sections of the process?
What is Cycle Stealing?
What are a Trap and Trapdoor?
Write the difference between program and process.
Write the difference between a user-level thread and a kernel-level thread.
Write down the advantages of multithreading.
Difference between Multithreading and Multitasking.

10. Practical Scenarios

How would you troubleshoot a system that is running slowly?
What steps would you take to recover from a system crash?
How would you handle a memory leak in a process?
Explain how you would debug a deadlock situation.

11. OS-Specific Questions

Explain the architecture of Linux.
What is the Windows Registry?
How does macOS handle memory management differently from Windows?
What is the role of the init process in Unix-based systems?
Write about monolithic kernel.

12. Coding and Implementation

Write a program to demonstrate the producer-consumer problem.
Implement a simple shell in C.
Write a program to simulate the Round Robin scheduling algorithm.
Implement a basic file system in Python.

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