Top 30 Most Common Os Viva Questions You Should Prepare For
Written by
James Miller, Career Coach
Preparing for technical interviews, especially those focusing on operating systems, can feel daunting. Often, these interviews include a "viva" component – a direct questioning session designed to probe your understanding of core concepts. Mastering the most common os viva questions is crucial for demonstrating foundational knowledge and confidence. This guide covers 30 essential OS topics frequently tested in viva scenarios, helping you anticipate questions and formulate clear, concise answers.
What Are os viva questions?
os viva questions are oral examination questions posed by interviewers to assess a candidate's grasp of operating system principles. Unlike coding challenges or design problems, these questions require direct definitions, explanations, and comparisons of OS concepts. They evaluate not just what you know, but how well you can articulate and apply that knowledge under pressure. Common areas include process management, memory management, file systems, and synchronization. Excelling in os viva questions shows you have a solid theoretical base.
Why Do Interviewers Ask os viva questions?
Interviewers use os viva questions to quickly gauge a candidate's fundamental understanding of how computing systems work at a low level. A strong grasp of OS concepts is vital for many roles, especially in systems programming, backend development, and any position dealing with performance or resource management. os viva questions help differentiate candidates by testing their ability to explain complex ideas simply and accurately, demonstrating critical thinking and problem-solving skills beyond writing code. They ensure you possess the necessary building blocks.
What is an Operating System?
What are the basic functions of an OS?
Explain Memory Management in OS.
What is Processor Management in OS?
What is Device Management in OS?
Explain File Management in OS.
What is Security in OS?
What is Accounting in OS?
What is Scheduling in OS?
What is Multitasking in OS?
What are the types of Operating Systems?
Define Virtual Memory.
What is a Thread in OS?
What is Deadlock in OS?
How do you avoid Deadlock in OS?
What is a CPU Scheduler?
Explain the Shortest Job First (SJF) Scheduling Algorithm.
What is Throughput in OS?
What is Context Switching in OS?
What is Paging in OS?
Explain Segmentation in OS.
What is Fragmentation in OS?
What is Swapping in OS?
What is a Process in OS?
What is a Program Counter in OS?
What is Synchronization in OS?
What is a semaphore in OS?
What is a Monitor in OS?
What is Race Condition in OS?
What is Starvation in OS?
Preview List
1. What is an Operating System?
Why you might get asked this:
This is a fundamental starting point. Interviewers want to ensure you know the core definition and purpose of an OS before diving into specifics, assessing basic understanding.
How to answer:
Define OS as intermediary software. Mention its role in managing hardware/software resources and providing essential services. Keep it concise and clear.
Example answer:
An OS is system software managing computer hardware and software resources. It acts as a layer between users and hardware, facilitating resource allocation, memory management, file handling, and process execution.
2. What are the basic functions of an OS?
Why you might get asked this:
Tests your knowledge of the primary responsibilities of an OS, demonstrating awareness of its diverse roles in managing system operations.
How to answer:
List key functions like memory management, process scheduling, file management, device management, and security. Briefly explain each or just list the main ones.
Example answer:
Basic functions include memory management, processor scheduling (CPU management), device management, file management, security, error detection, and accounting. These functions enable efficient system operation.
3. Explain Memory Management in OS.
Why you might get asked this:
Evaluates understanding of how the OS handles primary memory, a critical resource. It assesses knowledge of memory allocation, deallocation, and protection.
How to answer:
Describe its role in allocating and deallocating memory to processes. Mention goals like efficient use and preventing conflicts. Can touch upon concepts like paging or segmentation briefly.
Example answer:
Memory management is the OS function that manages the main memory. It involves allocating memory space to programs when they need it and deallocating it when they finish, ensuring efficient use and protection.
4. What is Processor Management in OS?
Why you might get asked this:
Probes your knowledge of how the OS manages the CPU, the central processing unit. This tests understanding of scheduling and process execution flow.
How to answer:
Explain it's about managing the CPU's usage by different processes. Mention CPU scheduling as the core activity, deciding which process runs when.
Example answer:
Processor management, or CPU scheduling, is how the OS allocates CPU time among various processes. It determines the order and duration for which processes get to use the CPU, aiming for efficiency and responsiveness.
5. What is Device Management in OS?
Why you might get asked this:
Assesses your knowledge of how the OS interacts with input/output devices, showing understanding of device drivers and resource allocation for peripherals.
How to answer:
Define it as managing I/O devices like printers, disks, etc. Mention it involves allocating devices to processes and handling communication via drivers.
Example answer:
Device management involves controlling and coordinating system hardware like keyboards, monitors, and disk drives. The OS manages access requests, allocates devices, and handles device I/O through device drivers.
6. Explain File Management in OS.
Why you might get asked this:
Tests understanding of how the OS organizes, stores, retrieves, and manages data on secondary storage, a fundamental user-facing function.
How to answer:
Describe its role in organizing data into files and directories. Mention operations like creation, deletion, access control, and storage allocation on disk.
Example answer:
File management is the OS's method for organizing and managing files and directories on storage devices. It provides structures for storing, accessing, protecting, and manipulating user data efficiently.
7. What is Security in OS?
Why you might get asked this:
Important for understanding how the OS protects system resources and user data from unauthorized access or malicious activities.
How to answer:
Explain it involves protecting system resources and user data. Mention mechanisms like user authentication, access control, and protection against viruses or unauthorized operations.
Example answer:
OS security involves protecting system resources (like files, memory, CPU) from unauthorized access or use. It includes authentication (verifying identity) and authorization (controlling access rights).
8. What is Accounting in OS?
Why you might get asked this:
Relevant in multi-user or networked environments, testing understanding of how resources are tracked and managed for different users or processes.
How to answer:
Describe it as tracking resource usage (CPU time, memory, disk space) by users or processes. Mention its use for billing, performance monitoring, or resource optimization.
Example answer:
Accounting in OS involves keeping track of resource utilization for different users or processes. This data helps monitor system performance, manage quotas, and for billing in multi-user systems.
9. What is Scheduling in OS?
Why you might get asked this:
A core OS concept. Interviewers want to know if you understand the process of deciding which task gets to run on the CPU and for how long.
How to answer:
Define it as the act of deciding which process gets the CPU next when multiple processes are ready. Mention the goal is efficient CPU utilization and responsiveness.
Example answer:
Scheduling is the process by which the OS decides which process among the ready queue should be allocated the CPU for execution, using various algorithms to optimize system goals.
10. What is Multitasking in OS?
Why you might get asked this:
Tests understanding of how a single CPU can appear to run multiple programs concurrently, a fundamental feature of modern OS.
How to answer:
Explain it's the OS's ability to execute multiple tasks or processes concurrently. Mention time-sharing as the mechanism, rapidly switching between tasks to create the illusion of parallel execution.
Example answer:
Multitasking allows a single user to run multiple applications or tasks simultaneously on a single CPU. The OS rapidly switches between tasks, giving each a slice of CPU time, creating concurrent execution.
11. What are the types of Operating Systems?
Why you might get asked this:
Assesses your broad knowledge of different OS categories based on user and task handling capabilities, showing awareness of OS evolution.
How to answer:
Classify OS based on user and task support (e.g., single-user/single-task, single-user/multi-task, multi-user/multi-task). Provide a brief example for each.
Example answer:
Types include: Single-User, Single-Task (e.g., old MS-DOS); Single-User, Multi-Task (e.g., Windows, macOS); Multi-User, Multi-Task (e.g., Unix, Linux, server Windows). Real-time OS is another type.
12. Define Virtual Memory.
Why you might get asked this:
A critical concept for understanding how OS manages memory illusion and supports programs larger than physical RAM.
How to answer:
Define it as a technique creating the illusion of a large main memory using disk space. Explain it allows programs to run even if they don't fit entirely in physical RAM by swapping pages.
Example answer:
Virtual memory is a memory management technique extending physical RAM by using disk space. It allows processes larger than physical memory to run and increases the degree of multiprogramming through paging or segmentation and swapping.
13. What is a Thread in OS?
Why you might get asked this:
Essential for modern concurrent programming. Tests your understanding of threads as lightweight processes sharing resources.
How to answer:
Define a thread as a single path of execution within a process. Highlight that threads within the same process share resources like memory space, unlike processes which are independent.
Example answer:
A thread is the smallest unit of execution within a process. Threads belonging to the same process share code, data, and open files, making them more lightweight and faster to context switch than processes.
14. What is Deadlock in OS?
Why you might get asked this:
A classic problem in concurrent systems. Tests understanding of the conditions under which processes can get stuck indefinitely.
How to answer:
Define it as a state where two or more processes are blocked, each waiting for a resource held by another process in the same set. Mention the circular waiting condition.
Example answer:
Deadlock is a situation where a set of processes are blocked because each process is holding a resource and waiting for another resource held by some other process in the set, leading to a standstill.
15. How do you avoid Deadlock in OS?
Why you might get asked this:
Follow-up to the deadlock definition. Tests knowledge of strategies to prevent deadlocks from occurring, like resource allocation protocols.
How to answer:
Briefly mention prevention (negating one of the four conditions) or avoidance techniques. Banker's Algorithm is a common example of avoidance.
Example answer:
Deadlock can be avoided by ensuring the system never enters an unsafe state where deadlock is possible. Techniques include avoidance algorithms like the Banker's Algorithm, which checks resource requests for safety.
16. What is a CPU Scheduler?
Why you might get asked this:
Focuses on the specific OS component responsible for scheduling decisions, linking theory to implementation.
How to answer:
Identify it as the OS module that selects the next process from the ready queue to be executed by the CPU. Mention its role in implementing scheduling algorithms.
Example answer:
A CPU scheduler is a part of the OS that determines which process among those ready to run should be given control of the CPU next, based on specific scheduling algorithms.
17. Explain the Shortest Job First (SJF) Scheduling Algorithm.
Why you might get asked this:
Tests knowledge of specific scheduling algorithms and their properties (optimality for minimum average waiting time).
How to answer:
Describe SJF: the process with the smallest estimated execution time is chosen next. Note its potential issue (starvation for long jobs) and if it's preemptive or non-preemptive.
Example answer:
SJF scheduling executes the process with the shortest estimated CPU burst duration first. It's known for minimizing average waiting time but can lead to starvation for longer processes if short jobs keep arriving.
18. What is Throughput in OS?
Why you might get asked this:
A key performance metric. Tests your understanding of how system efficiency is measured in terms of completed work.
How to answer:
Define throughput as the number of processes completed per unit of time. Explain it measures the work rate or efficiency of the system in processing tasks.
Example answer:
Throughput is an OS performance metric representing the number of processes or tasks successfully completed by the system within a specific period of time. Higher throughput means better efficiency.
19. What is Context Switching in OS?
Why you might get asked this:
Crucial for understanding multitasking and threading overhead. Tests knowledge of how the CPU switches between different executing units.
How to answer:
Describe it as saving the state (context) of the current process/thread and loading the state of the next one to be executed. Explain it's an overhead, but necessary for multitasking.
Example answer:
Context switching is the process of saving the state of a currently executing process or thread and restoring the state of the next one to be executed. It's the mechanism enabling multitasking, involving overhead.
20. What is Paging in OS?
Why you might get asked this:
Tests understanding of a fundamental virtual memory technique used for non-contiguous memory allocation and swapping.
How to answer:
Explain paging divides physical memory into fixed-size frames and logical memory into fixed-size pages. Programs are loaded into any available frames, potentially scattered in physical memory.
Example answer:
Paging is a memory management scheme where the OS retrieves data from secondary storage in same-size blocks called pages. Physical memory is divided into frames of the same size, allowing programs to occupy non-contiguous frames.
21. Explain Segmentation in OS.
Why you might get asked this:
Tests understanding of another memory management technique, contrasting it with paging by using variable-size logical units (segments).
How to answer:
Describe segmentation as dividing a program's logical address space into variable-size segments (e.g., code, data, stack). Explain each segment can be loaded independently into physical memory.
Example answer:
Segmentation is a memory management method where programs are divided into logical segments of variable sizes, such as code, data, or stack segments. Each segment is treated as a separate entity for loading into memory.
22. What is Fragmentation in OS?
Why you might get asked this:
Addresses a problem arising from memory allocation techniques, testing understanding of inefficient memory use.
How to answer:
Define fragmentation as wasted memory space. Differentiate between internal (within allocated blocks) and external (between allocated blocks) fragmentation and their causes.
Example answer:
Fragmentation is the condition where memory space is broken into small, unusable blocks. Internal fragmentation is unused space within an allocated block, while external fragmentation is free space scattered as small blocks.
23. What is Swapping in OS?
Why you might get asked this:
Tests understanding of a mechanism used with virtual memory to move processes between RAM and disk to increase multiprogramming.
How to answer:
Explain swapping as moving a process temporarily from main memory to disk (swap area) and then back into memory for execution. Used to free up memory for other processes.
Example answer:
Swapping is a memory management technique where an entire process can be temporarily moved from main memory to secondary storage (like a hard disk) and back again. It helps manage memory limitations.
24. What is a Process in OS?
Why you might get asked this:
Fundamental unit of execution. Tests understanding of what a process is and its components.
How to answer:
Define a process as a program in execution. Mention its components: program code, data, registers, program counter, and stack. Contrast with a program (passive entity).
Example answer:
A process is an instance of a program being executed. It is an active entity comprising the program code, its data, the program counter, CPU registers, and the operating system resources allocated to it.
25. What is a Program Counter in OS?
Why you might get asked this:
Specific component of a process. Tests understanding of instruction execution flow.
How to answer:
Define it as a register in the CPU that holds the memory address of the next instruction to be executed by the process.
Example answer:
The program counter (PC) is a register within the CPU that stores the memory address of the next instruction that the CPU will fetch and execute as part of a process's execution flow.
26. What is Synchronization in OS?
Why you might get asked this:
Crucial for understanding how concurrent processes/threads coordinate access to shared resources without interference.
How to answer:
Explain it as coordinating the execution of multiple processes or threads that share resources to ensure data consistency and prevent race conditions.
Example answer:
Synchronization in OS refers to mechanisms used to coordinate the execution of multiple processes or threads that access shared data or resources, ensuring proper timing and preventing inconsistent results.
27. What is a semaphore in OS?
Why you might get asked this:
Tests knowledge of a classic synchronization tool used for controlling access to shared resources.
How to answer:
Define a semaphore as a variable (integer or binary) used to control access by multiple processes to a common resource. Explain its operations: wait (P) and signal (V).
Example answer:
A semaphore is a synchronization primitive represented by an integer variable. It is accessed through two standard operations: wait (decrements the semaphore, blocks if zero) and signal (increments the semaphore).
28. What is a Monitor in OS?
Why you might get asked this:
Tests knowledge of a higher-level synchronization construct that simplifies concurrent programming compared to semaphores.
How to answer:
Define a monitor as a language construct providing mutual exclusion and condition variable support. Explain that only one process can be active inside a monitor at any time.
Example answer:
A monitor is a high-level language construct for synchronization. It encapsulates shared data and the procedures that operate on that data, ensuring that only one process can execute inside the monitor at a time.
29. What is Race Condition in OS?
Why you might get asked this:
Tests understanding of a potential problem in concurrent systems where the outcome depends on the unpredictable timing of events.
How to answer:
Explain it's a situation where multiple processes/threads access and manipulate shared data concurrently, and the final outcome depends on the order of execution, which can be unpredictable.
Example answer:
A race condition occurs when the timing or order of execution of multiple concurrent processes or threads accessing shared resources affects the program's outcome, potentially leading to incorrect results.
30. What is Starvation in OS?
Why you might get asked this:
Tests knowledge of a potential issue in scheduling or resource allocation where a process is indefinitely denied access to a resource.
How to answer:
Define starvation as a situation where a process is perpetually blocked from gaining access to a required resource or CPU time, even though the resource is available at times.
Example answer:
Starvation happens when a process is indefinitely delayed from accessing a resource or CPU because other processes are always given priority, preventing it from ever executing or completing its task.
Other Tips to Prepare for a os viva questions
Beyond memorizing definitions for os viva questions, focus on understanding the 'why' behind each concept. Practice explaining complex topics simply. As the saying goes, "If you can't explain it simply, you don't understand it well enough." Use diagrams or analogies if helpful during practice. Simulate interview conditions to get comfortable articulating your thoughts under pressure. Tools like Verve AI Interview Copilot (https://vervecopilot.com) can provide mock interview practice specifically tailored to technical fields, including operating systems, offering instant feedback to refine your answers to os viva questions. "Practice isn't just about repeating; it's about improving," noted a senior engineer. Use platforms that offer structured feedback to polish your responses to anticipated os viva questions. Leveraging AI-powered tools like Verve AI Interview Copilot can significantly enhance your preparation, making sure you're ready for any os viva questions thrown your way.
Frequently Asked Questions
Q1: How deep should my answers be?
A1: Aim for concise, accurate definitions and explanations. Elaborate if asked for more detail or examples.
Q2: Should I give examples from real OS?
A2: Yes, mentioning examples like Linux, Windows, or specific scenarios (like multi-threading in Java) is beneficial.
Q3: What if I don't know an answer?
A3: Be honest. State you don't know but might offer related concepts you understand or explain your thought process.
Q4: Are there common pitfalls in os viva questions?
A4: Giving vague definitions, confusing concepts (like process vs. thread), or over-explaining simple ideas.
Q5: How can I improve my articulation?
A5: Practice explaining concepts out loud to yourself or others. Record yourself to identify areas for improvement.
