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Operating System Interview Questions & Answers for Freshers, Experienced

Operating System Interview Questions

A program that performs as an intermediary between user and computer hardware is known as Operating System or OS. Freshers /experienced, who are going to attend OS interview can check level of Operating System Interview Questions & Answers from here.

The reason behind the establishment of Operating system is to provide a convenient environment in which the consumer can implement the program in a suitable and proficient manner. Aspirants who are going to attend OS Interview round can check complete Operating System Interview Questions & Answers from here.

Operating System Interview Questions

Operating System Interview Questions & Answers

Question 1: What is a socket?

Answer: A socket provides a connection between two applications. Each endpoint of a communication is a socket.

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Question 2: What is Direct Access Method?

Answer: Direct Access method is based on a disk model of a file, such that it is viewed as a numbered sequence of blocks or records. It allows arbitrary blocks to be read or written. Direct access is advantageous when accessing large amounts of information.

Question 3: What are interrupts?

Answer: 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.

Question 4: What is GUI?

Answer: GUI is short for Graphical User Interface. It provides users with an interface wherein actions can be performed by interacting with icons and graphical symbols. People find it easier to interact with the computer when in a GUI especially when using the mouse. Instead of having to remember and type commands, users just click on buttons to perform a process.

Question 5: When does thrashing occur?

Answer: Thrashing refers to an instance of high paging activity. This happens when it is spending more time paging instead of executing.

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Question 6: What is the best page size when designing an operating system?

Answer: The best paging size varies from system to system, so there is no single best when it comes to page size. There are different factors to consider in order to come up with a suitable page size, such as page table, paging time, and its effect on the overall efficiency of the operating system.

Question 7: When designing the file structure for an operating system, what attributes are considered?

Answer: Typically, the different attributes for a file structure are naming, identifier, supported file types, and location for the files, size, and level of protection.

Question 8: What are the primary functions of VFS?

Answer: VFS, or Virtual File System, separates file system generic operations from their implementation by defining a clean VFS interface. It is also based on a file-representation structure known as vnode, which contains a numerical designator needed to support network file systems.

Question 9: What are the different types of CPU registers in a typical operating system design?


  • Accumulators
  • Index Registers
  • Stack Pointer
  • General Purpose Registers

Types of System Call

System calls can be grouped roughly into five major categories:

System CallsExample
Process controlCreate process, terminate process, end, allocate and free memory etc
File manipulationCreate file, delete file, open file, close file, read, write.
Device manipulationrequest device, release device, read, write, reposition, get device attributes, set device attributes etc.
Information maintenanceget or set process, file, or device attributes
CommunicationsSend, receive messages, transfer status information

 Question 10: What is the purpose of an I/O status information?

Answer: I/O status information provides info about which I/O devices are to be allocated for a particular process. It also shows which files are opened, and other I/O device state.

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Question 11: What is multitasking?

Answer: Multitasking is the process within an operating system that allows the user to run several applications at the same time. However, only one application is active at a time for user interaction, although some applications can run “behind the scene”.

Question 12: What are some pros and cons of a command line interface?

Answer: A command line interface allows the user to type in commands that can immediately provide results. Many seasoned computer users are well accustomed to using the command line because they find it quicker and simpler. The main problem with a command line interface is that users have to be familiar with the commands, including the switches and parameters that come with it. This is a downside for people who are not fond of memorizing commands.

Question 13: What is caching?

Answer: Caching is the processing of utilizing a region of fast memory for a limited data and process. A cache memory is usually much efficient because of its high access speed.

Question 14: What is root partition?

Answer: Root partition is where the operating system kernel is located. It also contains other potentially important system files that are mounted during boot time.

Question 15: What are device drivers?

Answer: Device drivers provides a standard means of representing I/O devices that maybe manufactured by different companies. This prevents conflicts whenever such devices are incorporated in a systems unit.

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Question 16: What is spooling?

Answer: 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.

Question 17: What is an Assembler?

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

Question 18: What is preemptive multitasking?

Answer: Preemptive multitasking allows an operating system to switch between software programs. This in turn allows multiple programs to run without necessarily taking complete control over the processor and resulting in system crashes.

Question 19: How would a filename EXAMPLEFILE.TXT appear when viewed under the DOS command console operating in Windows 98?

Answer: The filename would appear as EXAMPL~1.TXT . The reason behind this is that filenames under this operating system is limited to 8 characters when working under DOS environment.

Question 20: Why is partitioning and formatting a prerequisite to installing an operating system?

Answer: Partitioning and formatting creates a preparatory environment on the drive so that the operating system can be copied and installed properly. This includes allocating space on the drive, designating a drive name, determining and creating the appropriate file system structure.

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Question 21: What is plumbing / piping?

Answer: It is the process of using the output of one program as an input to another. For example, instead of sending the listing of a folder or drive to the main screen, it can be piped and sent to a file, or sent to the printer to produce a hard copy.

Question 22: What is NOS?

Answer: NOS is short for Network Operating System. It is a specialized software that will allow a computer to communicate with other devices over the network, including file/folder sharing.

Question 23: Differentiate internal commands from external commands.

Answer: Internal commands are built-in commands that are already part of the operating system. External commands are separate file programs that are stored in a separate folder or directory.

Question 24: Under DOS, what command will you type when you want to list down the files in a directory, and at the same time pause after every screen output?


  1. dir /w
  2. dir /p
  3. dir /s
  4. dir /w /p
  5. dir /w /p

Answer: 4 (dir /w /p)

Question 25: Explain how you can reset Unity Configuration?

Answer: To reset the unity configuration the simplest way to do is to hit open a Terminal or hit Atl-F2 and run the command # unity –reset

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Functions of OS:

Operating system also controls and manages the use of the hardware among various applications programs for various uses.

By going through below given Operating System Interview Questions you can easily understand the level of questions asking in Operating System Interview round. Have a look on functions of Operating System:

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

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Candidates can get latest Operating System Interview Questions & Answers for Fresher’s and for Experienced from this page. Stay connected with this us through this web page to get latest updates about upcoming government/ private vacancies/ results/ admit Card etc.

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