Operating System-related Interview Questions

A list of top frequently asked Operating System-related interview questions and answers are given below.

1. What is an operating system?

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

2. What are the functions of OS?

Functions of OS:
There are many functions of the OS. Some of the important functions of OS are given below:

• Memory and Processor Management
• Providing user interface to users
• File Management and Device Management
• Scheduling of resources and jobs
• Error Detection
• Security

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3. What is the main purpose of an operating system?

There are two main purposes of an operating system:

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

4. Why is the operating system important?

OS is the most essential and vital part of a computer without which it is considered useless. It enables an interface or acts as a link for interaction between computer software that is installed on OS and users. It also helps to communicate with hardware and also maintains a balance between hardware and CPU. It also provides services to users and a platform for programs to run on. It performs all common tasks applications require.

5. What are the different operating systems?

• Batched operating systems
• Distributed operating systems
• Timesharing operating systems
• Multi-programmed operating systems
• Real-time operating systems

6. What is a socket?

A socket is used to make the connection between two applications. The endpoints of the connection are called sockets.

7. What is GUI?

GUI (Graphical User Interface) is basically a type of user interface that allows users to use graphics to interact with OS. GUI is created because it is more user-friendly, less complex, and easier to understand rather than a command-line interface. Its main goal is to increase efficiency and ease of use. Instead of having to memorize commands, users can just click on a button to simply execute the procedure. Examples of GUI include Microsoft Windows, macOS, Apple’s iOS, etc.

8. What is CLI?

CLI is short for Command Line Interface. This interface allows the user to type declarative commands to instruct the computer to perform operations. CLI offers greater flexibility. However, other users who are already accustomed to using GUI find it difficult to remember commands including attributes that come with it.

9. What is a real-time system?

A real-time system is used in the case when rigid-time requirements have been placed on the operation of a processor. It contains well-defined and fixed time constraints.

10. What is the difference between main memory and secondary memory.

Main memory: Main memory in a computer is RAM (Random Access Memory). It is also known as primary memory or read-write memory or internal memory. The programs and data that the CPU requires during the execution of a program are stored in this memory.
Secondary memory: Secondary memory in a computer are storage devices that can store data and programs. It is also known as external memory or additional memory or backup memory or auxiliary memory. Such storage devices are capable of storing high-volume data. Storage devices can be hard drives, USB flash drives, CDs, etc. 

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Primary Memory	Secondary Memory
Data can be directly accessed by the processing unit.	Firstly, data is transferred to primary memory and then routed to the processing unit.
It can be both volatile and non-volatile in nature.	It is non-volatile in nature.
It is more costly than secondary memory.	It is more cost-effective or less costly than primary memory.
It is temporary because data is stored temporarily.	It is permanent because data is stored permanently.
In this memory, data can be lost whenever there is a power failure.	In this memory, data is stored permanently and therefore cannot be lost even in case of power failure.
It is much faster than secondary memory and saves data that is currently used by the computer.	It is slower as compared to primary memory and saves different kinds of data in different formats.
It can be accessed by data.	It can be accessed by I/O channels.

11. What is virtual memory?

Virtual memory is a very useful memory management technique that enables processes to execute outside of memory. This technique is especially used when an executing program cannot fit in the physical memory.

12. What is kernel?

The kernel is the core and most important part of a computer operating system which provides basic services for all parts of the OS.

13. What do you mean by a process?

An executing program is known as a process. There are two types of processes:

• Operating System Processes
• User Processes

14. Explain the zombie process?

A zombie process, referred to as a defunct process, is basically a process that is terminated or completed but the whole process control block is not cleaned up from the main memory because it still has an entry in the process table to report to its parent process. It does not consume any of the resources and is dead, but it still exists. It also shows that resources are held by process and are not free.

15. Write top 10 examples of OS?

Some of the top OS that is used mostly are given below:

• MS-Windows
• Ubuntu
• Mac OS
• Fedora
• Solaris
• Free BSD
• Chrome OS
• CentOS
• Debian
• Android

16. What are device drivers?

Device drivers provide a standard means of representing I/O devices that may be manufactured by different companies. This prevents conflicts whenever such devices are incorporated into a systems unit.

17. What is the purpose of I/O status information?

I/O status information provides information about which I/O devices are to be allocated for a particular process. It also shows which files are opened, and another I/O device’s state

18. What is a command interpreter?

It is a program that interprets the command input through a keyboard or command batch file. It helps the user to interact with the OS and trigger the required system programs or execute some user application.

19. What is a daemon?

Disk and execution monitor is a process that runs in the background without the user’s interaction. They usually start at the booting time and terminate when the system is shut down.

20. What are read-write locks?

Read-write locks provide simultaneous read access to many threads while the write access stays with one thread at a time. They are especially useful in protecting the data that is not frequently written but read simultaneously by many threads.

• They are slower than mutexes.

21. What is a deadlock?

It is a condition where a group of two or more waiting for the resources currently in use by other processes of the same group.

• In this situation, every process is waiting for an event to be triggered by another process of the group.
• Since no thread can free up the resource a deadlock occurs and the application hangs.

22. What is spooling?

Spooling is normally associated with printing. When different applications want to send an output to the printer at the same time, spooling takes all of these print jobs into a disk file and queues them accordingly to the printer.

23. What is an Assembler?

An assembler acts as a translator for low-level language. Assembly codes written using mnemonic commands are translated by the Assembler into machine language.

24. What are interrupts?

Interrupts are part of a hardware mechanism that sends a notification to the CPU when it wants to gain access to a particular resource. An interrupt handler receives this interrupt signal and “tells” the processor to take action based on the interrupt request.

25. What is RAID? What are the different RAID levels?

RAID stands for Redundant Array of Independent Disks. It is used to store the same data redundantly to improve the overall performance.

Following are the different RAID levels:

• RAID 0 – Striped Disk Array without fault tolerance
• RAID 1 – Mirroring and duplexing
• 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