Top 30 Operating System Interview Questions (With Answers)

Preparing for a tech interview can feel overwhelming, especially when operating systems (OS) come into play—they’re the backbone of how computers manage resources and run applications. Whether you’re aiming for a software engineering role or a systems admin position, nailing OS concepts shows you understand the fundamentals of computing. In this post, we’ll dive deep into 30 high-quality OS interview questions that have been actually asked in real interviews at companies like Google, Amazon, and other FAANG giants. These aren’t just theoretical; they’re drawn from common experiences shared by candidates on platforms like LeetCode, Glassdoor, and tech forums. We’ll break them down with detailed explanations, examples, and tips to help you respond confidently. Plus, to stay ahead with free course updates and resources on topics like this, sign up for our newsletter and get exclusive access to the latest learning materials.

If you’re brushing up on related skills, consider exploring structured courses to solidify your foundation. For instance, mastering data structures and algorithms often complements OS knowledge—check out our comprehensive DSA course for hands-on practice.

Why Operating Systems Matter in Interviews

Operating systems are crucial because they handle everything from process management to memory allocation, ensuring software runs efficiently. Interviewers ask these questions to gauge your understanding of how systems work under the hood, especially in scenarios involving performance, concurrency, and resource optimization. Based on reports from real interviews, questions often focus on processes, threads, memory, and synchronization—areas where mistakes can lead to system crashes or inefficiencies.

In FAANG interviews, OS questions test not just rote knowledge but your ability to apply concepts to real-world problems, like debugging a deadlock or optimizing virtual memory. Expect a mix of basic definitions and advanced troubleshooting. Let’s start with the basics and build up.

Basic OS Interview Questions

These foundational questions are often the starting point in interviews, helping interviewers assess your core knowledge. They’re commonly asked in entry-level or general tech roles.

1. What is an operating system, and what are its main functions?

An operating system (OS) is system software that manages computer hardware and software resources, providing common services for computer programs. Think of it as the middleman between you and the hardware—it ensures everything runs smoothly without you needing to worry about low-level details.

Key functions include:

• Process Management: Creating, scheduling, and terminating processes.
• Memory Management: Allocating and deallocating memory space.
• File System Management: Handling file creation, deletion, and access.
• Device Management: Controlling hardware like printers and disks.
• Security and Protection: Preventing unauthorized access.

For example, when you open a web browser, the OS allocates memory and CPU time to it. Without an OS, you’d have to manually manage these resources, which is impractical. In interviews, emphasize how the OS abstracts hardware complexities for users.

2. What is the difference between a process and a thread?

This is a classic question asked in nearly every OS interview, as it tests your grasp of concurrency.

• Process: An independent program in execution with its own memory space, resources, and address space. Processes are heavyweight and isolated, meaning they don’t share memory directly.
• Thread: A lightweight subunit of a process that shares the same memory space and resources as other threads in the process. Threads are faster to create and switch between but can lead to issues like race conditions if not synchronized.

Example: In a web server, multiple threads handle client requests within one process, improving efficiency. Tip: Mention that threads are ideal for tasks like I/O-bound operations.

3. What is a kernel, and what are its types?

The kernel is the core component of an OS that manages system resources and acts as a bridge between applications and hardware. It’s always in memory and handles low-level tasks like process scheduling and interrupt handling.

Types:

• Monolithic Kernel: All OS services (file system, device drivers) run in kernel space for high performance but can be less stable (e.g., Linux).
• Microkernel: Only essential services in kernel space; others in user space for better modularity and security (e.g., MINIX).
• Hybrid Kernel: Combines both for balance (e.g., Windows NT).

In real interviews at companies like Amazon, you might be asked how a monolithic kernel impacts system crashes—since everything is interconnected, one fault can bring down the whole system.

4. Explain virtual memory and how it works.

Virtual memory allows a computer to use more memory than physically available by temporarily transferring data to disk storage. It creates an illusion of a large contiguous memory space.

How it works:

• Memory is divided into pages (virtual) and frames (physical).
• When a program needs data not in RAM, a page fault occurs, and the OS swaps it from disk (paging) or segments.
• Benefits: Multitasking, efficient memory use; Drawbacks: Thrashing if overused.

Example: Running multiple apps on a 8GB RAM machine—virtual memory uses SSD as extension. For deeper prep, our crash course covers memory management techniques.