Interview Questions - CareerGuru99

Question 1

Explain the main purpose of an operating system?

Answer 1

Operating systems exist for two main purposes. One is that it is designed to make sure a computer system performs well by managing its computational activities. Another is that it provides an environment for the development and execution of programs.

Question 2

What is demand paging?

Answer 2

Demand paging is referred when not all of a process’s pages are in the RAM, then the OS brings the missing(and required) pages from the disk into the RAM.

Question 3

What are the advantages of a multiprocessor system?

Answer 3

With an increased number of processors, there is a considerable increase in throughput. It can also save more money because they can share resources. Finally, overall reliability is increased as well.

Question 4

What is kernel?

Answer 4

A kernel is the core of every operating system. It connects applications to the actual processing of data. It also manages all communications between software and hardware components to ensure usability and reliability.

Question 5

What are real-time systems?

Answer 5

Real-time systems are used when rigid time requirements have been placed on the operation of a processor. It has well defined and fixed time constraints.

Question 6

What is a virtual memory?

Answer 6

Virtual memory is a memory management technique for letting processes execute outside of memory. This is very useful especially is an executing program cannot fit in the physical memory.

Question 7

Describe the objective of multiprogramming.

Answer 7

The main objective of multiprogramming is to have a process running at all times. With this design, CPU utilization is said to be maximized.

Question 8

What is time- sharing system?

Answer 8

In a Time-sharing system, the CPU executes multiple jobs by switching among them, also known as multitasking. This process happens so fast that users can interact with each program while it is running.

Question 9

What is SMP?

Answer 9

SMP is a short form of Symmetric Multi-Processing. It is the most common type of multiple-processor systems. In this system, each processor runs an identical copy of the operating system, and these copies communicate with one another as needed.

Question 10

How are server systems classified?

Answer 10

Server systems can be classified as either computer-server systems or file server systems. In the first case, an interface is made available for clients to send requests to perform an action. In the second case, provisions are available for clients to create, access and update files.

Question 11

What is asymmetric clustering?

Answer 11

In asymmetric clustering, a machine is in a state known as hot standby mode where it does nothing but to monitor the active server. That machine takes the active server’s role should the server fails.

Question 12

What is a thread?

Answer 12

A thread is a basic unit of CPU utilization. In general, a thread is composed of a thread ID, program counter, register set, and the stack.

Question 13

Give some benefits of multithreaded programming.

Answer 13

– there is increased responsiveness to the user
– resource sharing within the process
– economy
– utilization of multiprocessing architecture

Question 14

Briefly explain FCFS.

Answer 14

FCFS stands for First-come, first-served. It is one type of scheduling algorithm. In this scheme, the process that requests the CPU first is allocated the CPU first. Implementation is managed by a FIFO queue.

Question 15

What is RR scheduling algorithm?

Answer 15

RR (round-robin) scheduling algorithm is primarily aimed for time-sharing systems. A circular queue is a setup in such a way that the CPU scheduler goes around that queue, allocating CPU to each process for a time interval of up to around 10 to 100 milliseconds.

Question 16

What are necessary conditions which can lead to a deadlock situation in a system?

Answer 16

Deadlock situations occur when four conditions occur simultaneously in a system: Mutual exclusion; Hold and Wait; No preemption; and Circular wait.

Question 17

Enumerate the different RAID levels.

Answer 17

RAID 0 – Non-redundant striping
RAID 1 – Mirrored Disks
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

Question 18

Describe Banker’s algorithm

Answer 18

Banker’s algorithm is one form of deadlock-avoidance in a system. It gets its name from a banking system wherein the bank never allocates available cash in such a way that it can no longer satisfy the needs of all of its customers.

Question 19

What factors determine whether a detection-algorithm must be utilized in a deadlock avoidance system?

Answer 19

One is that it depends on how often a deadlock is likely to occur under the implementation of this algorithm. The other has to do with how many processes will be affected by deadlock when this algorithm is applied.

Question 20

State the main difference between logical from physical address space.

Answer 20

Logical address refers to the address that is generated by the CPU. On the other hand, physical address refers to the address that is seen by the memory unit.

Question 21

How does dynamic loading aid in better memory space utilization?

Answer 21

With dynamic loading, a routine is not loaded until it is called. This method is especially useful when large amounts of code are needed in order to handle infrequently occurring cases such as error routines.

Question 22

What are overlays?

Answer 22

Overlays are used to enable a process to be larger than the amount of memory allocated to it. The basic idea of this is that only instructions and data that are needed at any given time are kept in memory.

Question 23

What is the basic function of paging?

Answer 23

Paging is a memory management scheme that permits the physical address space of a process to be noncontiguous. It avoids the considerable problem of having to fit varied sized memory chunks onto the backing store.

Question 24

What is fragmentation?

Answer 24

Fragmentation is memory wasted. It can be internal if we are dealing with systems that have fixed-sized allocation units, or external if we are dealing with systems that have variable-sized allocation units.

Question 25

How does swapping result in better memory management?

Answer 25

During regular intervals that are set by the operating system, processes can be copied from main memory to a backing store, and then copied back later. Swapping allows more operations to be run that can fit into memory at one time

Question 26

Give an example of a Process State.

Answer 26

– New State – means a process is being created
– Running – means instructions are being executed
– Waiting – means a process is waiting for certain conditions or events to occur
– Ready – means a process is waiting for an instruction from the main processor
– Terminate – means a process is stopped abruptly

Question 27

What is a socket?

Answer 27

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

Question 28

What is Direct Access Method?

Answer 28

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 29

When does thrashing occur?

Answer 29

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

Question 30

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

Answer 30

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 31

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

Answer 31

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 32

What is root partition?

Answer 32

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 33

What are device drivers?

Answer 33

Device drivers provide 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.

Question 34

What are the primary functions of VFS?

Answer 34

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

Question 35

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

Answer 35

– Accumulators
– Index Registers
– Stack Pointer
– General Purpose Registers

Question 36

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

Answer 36

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 other I/O device state.

Question 37

What is multitasking?

Answer 37

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 38

Explain pros and cons of a command line interface?

Answer 38

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.

However, 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 39

What is caching?

Answer 39

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 40

What is spooling?

Answer 40

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 41

What is an Assembler?

Answer 41

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 42

What are interrupts?

Answer 42

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 43

What is GUI?

Answer 43

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 click on buttons to perform a process.

Question 44

What is preemptive multitasking?

Answer 44

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 45

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

Answer 45

Partitioning and formatting create 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 and structure.

Question 46

What is plumbing/piping?

Answer 46

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 47

What is NOS?

Answer 47

OS 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 48

Differentiate internal commands from external commands.

Answer 48

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 49

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?

a) dir /w
b) dir /p
c) dir /s
d) dir /w /p

Answer 49

Answer: d) dir /w /p

Question 50

How would a file name EXAMPLEFILE.TXT appear when viewed under the DOS command console operating in Windows 98?

Answer 50

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

Question 51

What is a folder in Ubuntu?

Answer 51

There is no concept of Folder in Ubuntu. Everything included in your hardware is a FILE.

Question 52

Explain why Ubuntu is safe and not affected by viruses?

Answer 52

• It does not support malicious e-mails and contents, and before any e-mail is opened by users it will go through many security checks
• Ubuntu uses Linux, which is a super secure O.S system
• Unlike other O.S, countless Linux users can see the code at any time and can fix the problem if there is any
• Malware and viruses are coded to take advantage of the weakness in Windows

Question 53

Explain what is Unity in Ubuntu? How can you add new entries to the launcher?

Answer 53

In Ubuntu, Unity is the default graphical shell. On the left side of the Ubuntu, it introduces the launcher and Dash to start programs.

In order to add new entries to the launcher, you can create a file name like .desktop and then drag the file on the launcher.

Question 54

Explain the purpose of using a libaio package in Ubuntu?

Answer 54

Libaio is Linux Kernel Asynchronous I/O (A/O). A/O allows even a single application thread to overlap I/O operations with other processing, by providing an interface for submitting one or more I/O requests in one system call without waiting for completion. And a separate interface to reap completed I/O operations associated with a given completion group.

Question 55

What is the use of behavior tab in Ubuntu?

Answer 55

Through behaviors tab, you can make many changes on the appearance of the desktop

• Auto-hide the launcher: You can use this option to reveal the launcher when moving the pointer to the defined hot spot.
• Enable workspaces: By checking this option, you can enable workspace
• Add show desktop icon to the launcher: This option is used to display the desktop icon on the launcher

Question 56

What is the meaning of “export” command in Ubuntu?

Answer 56

Export is a command in Bash shell language. When you try to set a variable, it is visible or exported to any subprocess started from that instance of bash. The variable will not exist in the sub-process without the export command.

Question 57

Explain how you can reset Unity Configuration?

Answer 57

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

Question 58

Explain how to access Terminal?

Answer 58

To access terminal, you have to go under Application Menu -> Accessories -> Terminal.