OS MCQ

1. What is an operating system?

a) interface between the hardware and application programs
b) collection of programs that manages hardware resources
c) system service provider to the application programs
d) all of the mentioned
View Answer

Answer: d

Explanation: An Operating System acts as an intermediary between user/user

applications/application programs and hardware. It is a program that manages hardware
resources. It provides services to application programs.

2. What is the main function of the command interpreter?

a) to provide the interface between the API and application program
b) to handle the files in the operating system
c) to get and execute the next user-specified command
d) none of the mentioned
View Answer

Answer: c

Explanation: The main function of a command interpreter is to get and execute the next
user-specified command. Command Interpreter checks for valid command and then runs
that command else it will throw an error.

3. In Operating Systems, which of the following is/are CPU scheduling algorithms?

a) Priority
b) Round Robin
c) Shortest Job First
d) All of the mentioned
View Answer
 Answer: d

Explanation: In Operating Systems, CPU scheduling algorithms are:

i) First Come First Served scheduling

ii) Shortest Job First scheduling

iii) Priority scheduling

iv) Round Robin scheduling

v) Multilevel Queue scheduling

vi) Multilevel Feedback Queue scheduling

All of these scheduling algorithms have their own advantages and disadvantages.

4. To access the services of the operating system, the interface is provided by the
___________
a) Library
b) System calls
c) Assembly instructions
d) API
View Answer

Answer: b

Explanation: To access services of the Operating System an interface is provided by the

System Calls. Generally, these are functions written in C and C++. Open, Close, Read,
Write are some of most prominently used system calls.

5. CPU scheduling is the basis of ___________

a) multiprogramming operating systems
b) larger memory sized systems
c) multiprocessor systems
d) none of the mentioned
View Answer

Answer: a

Explanation: None.

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6. Which one of the following is not true?
a) kernel remains in the memory during the entire computer session
b) kernel is made of various modules which can not be loaded in running operating system
c) kernel is the first part of the operating system to load into memory during booting
d) kernel is the program that constitutes the central core of the operating system
View Answer

Answer: b

Explanation: Kernel is the first program that is loaded in memory when OS is loading as
well as it remains in memory till OS is running. Kernel is the core part of the OS which is
responsible for managing resources, allowing multiple processes to use the resources
and provide services to various processes. Kernel modules can be loaded and unloaded
in run-time i.e. in running OS.

7. Which one of the following errors will be handle by the operating system?
a) lack of paper in printer
b) connection failure in the network
c) power failure
d) all of the mentioned
View Answer

Answer: d

Explanation: All the mentioned errors are handled by OS. The OS is continuously
monitoring all of its resources. Also, the OS is constantly detecting and correcting errors.

8. Where is the operating system placed in the memory?

a) either low or high memory (depending on the location of interrupt vector)
b) in the low memory
c) in the high memory
d) none of the mentioned
View Answer

Answer: a

Explanation: None.

9. If a process fails, most operating system write the error information to a ______
a) new file
b) another running process
c) log file
d) none of the mentioned
View Answer

Answer: c

Explanation: If a process fails, most operating systems write the error information to a log
file. Log file is examined by the debugger, to find out what is the actual cause of that
particular problem. Log file is useful for system programmers for correcting errors.

10. Which one of the following is not a real time operating system?
a) RTLinux
b) Palm OS
c) QNX
d) VxWorks
View Answer

Answer: b

Explanation: VxWorks, QNX & RTLinux are real-time operating systems. Palm OS is a
mobile operating system. Palm OS is developed for Personal Digital Assistants (PDAs).

11. What does OS X has?

a) monolithic kernel with modules
b) microkernel
c) monolithic kernel
d) hybrid kernel
View Answer
 Answer: d

Explanation: OS X has a hybrid kernel. Hybrid kernel is a combination of two different

kernels. OS X is developed by Apple and originally it is known as Mac OS X.

12. In operating system, each process has its own __________

a) open files
b) pending alarms, signals, and signal handlers
c) address space and global variables
d) all of the mentioned
View Answer

Answer: d

Explanation: In Operating Systems, each process has its own address space which
contains code, data, stack, and heap segments or sections. Each process also has a list
of files that is opened by the process as well as all pending alarms, signals, and various
signal handlers.

13. In a timeshare operating system, when the time slot assigned to a process is completed,
the process switches from the current state to?
a) Suspended state
b) Terminated state
c) Ready state
d) Blocked state
View Answer

Answer: c

Explanation: In a time-sharing operating system, when the time slot given to a process is
completed, the process goes from the running state to the Ready State. In a time-sharing
operating system, unit time is defined for sharing CPU, it is called a time quantum or time
slice. If a process takes less than 1 time quantum, then the process itself releases the
CPU.

14. Cascading termination refers to the termination of all child processes if the parent
process terminates ______
a) Normally or abnormally
b) Abnormally
c) Normally
d) None of the mentioned
View Answer

Answer: a

Explanation: Cascading termination refers to the termination of all child processes if the
parent process terminates Normally or Abnormally. Some systems don’t allow child
processes to exist if the parent process has terminated. Cascading termination is
normally initiated by the operating system.

15. When a process is in a “Blocked” state waiting for some I/O service. When the service is
completed, it goes to the __________
a) Terminated state
b) Suspended state
c) Running state
d) Ready state
View Answer

Answer: d

Explanation: Suppose that a process is in “Blocked” state waiting for some I/O service.
When the service is completed, it goes to the ready state. Process never goes directly to
the running state from the waiting state. Only processes which are in ready state go to
the running state whenever CPU allocated by operating system.

16. Transient operating system code is a code that ____________

a) stays in the memory always
b) never enters the memory space
c) comes and goes as needed
d) is not easily accessible
View Answer

Answer: c

Explanation: None.

17. The portion of the process scheduler in an operating system that dispatches processes
is concerned with ____________
a) assigning ready processes to waiting queue
b) assigning running processes to blocked queue
c) assigning ready processes to CPU
d) all of the mentioned
View Answer

Answer: c

Explanation: None.

18. The FCFS algorithm is particularly troublesome for ____________

a) operating systems
b) multiprocessor systems
c) time sharing systems
d) multiprogramming systems
View Answer

Answer: c

Explanation: In a time sharing system, each user needs to get a share of the CPU at
regular intervals.

19. For an effective operating system, when to check for deadlock?

a) every time a resource request is made at fixed time intervals
b) at fixed time intervals
c) every time a resource request is made
d) none of the mentioned
View Answer

Answer: a

Explanation: In an effective operating system, we must verify the deadlock each time a
request for resources is made at fixed time intervals.

20. A deadlock avoidance algorithm dynamically examines the __________ to ensure that a
circular wait condition can never exist.
a) operating system
b) resources
c) system storage state
d) resource allocation state
View Answer

Answer: d

Explanation: Resource allocation states are used to maintain the availability of the
already and current available resources.

21. Swapping _______ be done when a process has pending I/O, or has to execute I/O
operations only into operating system buffers.
a) must never
b) maybe
c) can
d) must
View Answer

Answer: a

Explanation: None.

22. The main memory accommodates ____________

a) cpu
b) user processes
c) operating system
d) all of the mentioned
View Answer

Answer: c

Explanation: None.

23. The operating system is responsible for?

a) bad-block recovery
b) booting from disk
c) disk initialization
d) all of the mentioned
View Answer

Answer: d
 Explanation: None.

24. The operating system and the other processes are protected from being modified by an
already running process because ____________
a) every address generated by the CPU is being checked against the relocation and limit
registers
b) they have a protection algorithm
c) they are in different memory spaces
d) they are in different logical addresses
View Answer

Answer: a

Explanation: None.

25. Using transient code, _______ the size of the operating system during program
execution.
a) maintains
b) changes
c) increases
d) decreases
View Answer

Answer: b

Explanation: None.

26. The operating system maintains a ______ table that keeps track of how many frames
have been allocated, how many are there, and how many are available.
a) memory
b) mapping
c) page
d) frame
View Answer

Answer: d

Explanation: None.
27. To obtain better memory utilization, dynamic loading is used. With dynamic loading, a
routine is not loaded until it is called. For implementing dynamic loading ____________
a) special support from operating system is essential
b) special support from hardware is required
c) user programs can implement dynamic loading without any special support from
hardware or operating system
d) special support from both hardware and operating system is essential
View Answer

Answer: c

Explanation: None.

28. The _________ presents a uniform device-access interface to the I/O subsystem, much
as system calls provide a standard interface between the application and the operating
system.
a) Device drivers
b) I/O systems
c) Devices
d) Buses
View Answer

Answer: a

Explanation: None.

29. In real time operating system ____________

a) process scheduling can be done only once
b) all processes have the same priority
c) kernel is not required
d) a task must be serviced by its deadline period
View Answer

Answer: d

Explanation: None.

30. Hard real time operating system has ______________ jitter than a soft real time
operating system.
a) equal
b) more
c) less
d) none of the mentioned
View Answer

Answer: c

Explanation: Jitter is the undesired deviation from the true periodicity.

31. For real time operating systems, interrupt latency should be ____________
a) zero
b) minimal
c) maximum
d) dependent on the scheduling
View Answer

Answer: b

Explanation: Interrupt latency is the time duration between the generation of interrupt and
execution of its service.

32. Which one of the following is a real time operating system?

a) Windows CE
b) RTLinux
c) VxWorks
d) All of the mentioned
View Answer

Answer: d

Explanation: None.

33. The priority of a process will ______________ if the scheduler assigns it a static priority.
a) depends on the operating system
b) change
c) remain unchanged
d) none of the mentioned
View Answer
 Answer: c

Explanation: None.

34. What are the characteristics of Host based IDS?

a) Logs are analysed to detect tails of intrusion
b) The host operating system logs in the audit information
c) Logs includes logins, file opens, and program executions
d) All of the mentioned
View Answer

Answer: d

Explanation: None.

35. What are the characteristics of stack based IDS?

a) It is programmed to interpret a certain series of packets
b) It models the normal usage of the network as a noise characterization
c) They are integrated closely with the TCP/IP stack and watch packets
d) The host operating system logs in the audit information
View Answer

Answer: c

Explanation: None.

36. If the sum of the working – set sizes increases, exceeding the total number of available
frames ____________
a) the operating system selects a process to suspend
b) the system crashes
c) then the process crashes
d) the memory overflows
View Answer

Answer: a

Explanation: None.
37. The information about all files is kept in ____________
a) operating system
b) separate directory structure
c) swap space
d) none of the mentioned
View Answer

Answer: b

Explanation: None.

38. The operating system keeps a small table containing information about all open files
called ____________
a) file table
b) directory table
c) open-file table
d) system table
View Answer

Answer: c

Explanation: None.

39. What will happen in the single level directory?

a) All files are contained in the same directory
b) All files are contained in different directories all at the same level
c) Depends on the operating system
d) None of the mentioned
View Answer

Answer: a

Explanation: None.

40. The operating system _______ the links when traversing directory trees, to preserve the
acyclic structure of the system.
a) deletes
b) considers
c) ignores
d) none of the mentioned
View Answer

Answer: c

Explanation: None.

41. To recover from failures in the network operations _____________ information may be
maintained.
a) operating system
b) ip address
c) stateless
d) state
View Answer

Answer: d

Explanation: None.

42. On systems where there are multiple operating system, the decision to load a particular
one is done by _____________
a) process control block
b) file control block
c) boot loader
d) bootstrap
View Answer

Answer: c

Explanation: None.

43. Whenever a process needs I/O to or from a disk it issues a ______________

a) system call to the operating system
b) a special procedure
c) system call to the CPU
d) all of the mentioned
View Answer

Answer: a
 Explanation: None.

44. The two steps the operating system takes to use a disk to hold its files are _______ and
________
a) caching & logical formatting
b) logical formatting & swap space creation
c) swap space creation & caching
d) partitioning & logical formatting
View Answer

Answer: d

Explanation: None.

45. The _______ program initializes all aspects of the system, from CPU registers to device
controllers and the contents of main memory, and then starts the operating system.
a) bootstrap
b) main
c) bootloader
d) rom
View Answer

Answer: a

Explanation: None.

46. In SCSI disks used in high end PCs, the controller maintains a list of _________ on the
disk. The disk is initialized during ________ formatting which sets aside spare sectors not
visible to the operating system.
a) destroyed blocks, partitioning
b) bad blocks, low level formatting
c) destroyed blocks, high level formatting
d) bad blocks, partitioning
View Answer

Answer: b

Explanation: None.
47. Which principle states that programs, users, and even the systems be given just enough
privileges to perform their task?
a) principle of least privilege
b) principle of process scheduling
c) principle of operating system
d) none of the mentioned
View Answer

Answer: a

Explanation: None.

48. Network operating system runs on ___________

a) every system in the network
b) server
c) both server and every system in the network
d) none of the mentioned
View Answer

Answer: b

Explanation: None.

49. What are the types of distributed operating systems?

a) Zone based Operating system
b) Level based Operating system
c) Network Operating system
d) All of the mentioned
View Answer

Answer: c

Explanation: None.

50. In Unix, which system call creates the new process?

a) create
b) fork
c) new
d) none of the mentioned
View Answer

Answer: b

Explanation: In UNIX, a new process is created by fork() system call. fork() system call
returns a process ID which is generally the process id of the child process created.