Category: Operating System Objective Questions

Operating System Multiple Choice Questions on “Paging”.

1. Physical memory is broken into fixed-sized blocks called ________
a) frames
b) pages
c) backing store
d) none of the mentioned

Answer: a
Clarification: None.

2. Logical memory is broken into blocks of the same size called _________
a) frames
b) pages
c) backing store
d) none of the mentioned

Answer: b
Clarification: None.

3. Every address generated by the CPU is divided into two parts. They are ____________
a) frame bit & page number
b) page number & page offset
c) page offset & frame bit
d) frame offset & page offset

Answer: b
Clarification: None.

4. The __________ is used as an index into the page table.
a) frame bit
b) page number
c) page offset
d) frame offset

Answer: b
Clarification: None.

5. The _____ table contains the base address of each page in physical memory.
a) process
b) memory
c) page
d) frame

Answer: c
Clarification: None.

6. The size of a page is typically ____________
a) varied
b) power of 2
c) power of 4
d) none of the mentioned

Answer: b
Clarification: None.

7. If the size of logical address space is 2 to the power of m, and a page size is 2 to the power of n addressing units, then the high order _____ bits of a logical address designate the page number, and the ____ low order bits designate the page offset.
a) m, n
b) n, m
c) m – n, m
d) m – n, n

Answer: d
Clarification: None.

8. With paging there is no ________ fragmentation.
a) internal
b) external
c) either type of
d) none of the mentioned

Answer: b
Clarification: None.

9. 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) page
b) mapping
c) frame
d) memory

Answer: c
Clarification: None.

10. Paging increases the ______ time.
a) waiting
b) execution
c) context – switch
d) all of the mentioned

Answer: c
Clarification: None.

11. Smaller page tables are implemented as a set of _______
a) queues
b) stacks
c) counters
d) registers

Answer: d
Clarification: None.

12. The page table registers should be built with _______
a) very low speed logic
b) very high speed logic
c) a large memory space
d) none of the mentioned

Answer: b
Clarification: None.

13. For larger page tables, they are kept in main memory and a __________ points to the page table.
a) page table base register
b) page table base pointer
c) page table register pointer
d) page table base

Answer: a
Clarification: None.

14. For every process there is a __________
a) page table
b) copy of page table
c) pointer to page table
d) all of the mentioned

Answer: a
Clarification: None.

15. Time taken in memory access through PTBR is ____________
a) extended by a factor of 3
b) extended by a factor of 2
c) slowed by a factor of 3
d) slowed by a factor of 2

Answer: d

Operating System Questions and Answers on “Multimedia System – Network Management” and will also be useful for campus interviews.

1. The three general methods for delivering content from a server to a client across a network are ___________
a) unicasting
b) multicasting
c) broadcasting
d) all of the mentioned

Answer: d
Clarification: None.

2. Unicasting delivers the content to ___________
a) a single client
b) all clients, regardless whether they want the content or not
c) a group of receivers who indicate they wish to receive the content
d) none of the mentioned

Answer: a
Clarification: None.

3. Broadcasting delivers the content to ___________
a) a single client
b) all clients, regardless whether they want the content or not
c) a group of receivers who indicate they wish to receive the content
d) none of the mentioned

Answer: b
Clarification: None.

4. Multicasting delivers the content to ___________
a) a single client
b) all clients, regardless whether they want the content or not
c) a group of receivers who indicate they wish to receive the content
d) none of the mentioned

Answer: c
Clarification: None.

5. RTSP stands for ___________
a) Real Time Streaming Policy
b) Real Time Streaming Protocol
c) Real Time Systems Protocol
d) Read Time Streaming Policy

Answer: b
Clarification: None.

6. HTTP is __________
a) a stateful protocol
b) a stateless protocol
c) a protocol that maintains the status of its connection with the client
d) a stateless protocol that does not maintain the status of its connection with the client

Answer: d
Clarification: None.

7. RTSP includes which of the following states?
a) SETUP
b) PLAY
c) PAUSE
d) All of the mentioned

Answer: d
Clarification: None.

8. In the SETUP state ___________
a) the server is setup
b) the client is setup
c) the server allocates resources for the client session
d) the client sends requests to the server

Answer: c
Clarification: None.

9. In the TEARDOWN state ___________
a) the server breaks down the connection and releases the resources allocated for the session
b) the client breaks down the connection and releases the resources allocated for the session
c) the system crashes
d) none of the mentioned

Answer: a
Clarification: None.

10. RTP stands for ___________
a) real time protocol
b) real time transmission control protocol
c) real time transmission protocol
d) real time transport protocol

Answer: d
Clarification: None.

11. The problem with unicast delivery is that the ___________
a) memory allocation is difficult
b) server must establish a separate unicast session for each client
c) the routers must support unicasting
d) the clients must be close to the server

Answer: b
Clarification: None.

12. The difficulty with multicasting from a practical point of view is ___________
a) memory allocation is difficult
b) server must establish a separate unicast session for each client
c) the routers must support multicasting
d) none of the mentioned

Answer: c
Clarification: None.

13. To let a client have random access to a media stream with ___________
a) the protocol used must not be stateless
b) the server must support download
c) the stream should give access rights to the client
d) all of the mentioned

Answer: a

Operating System Multiple Choice Questions on “Virtual Memory – Demand Paging”.

1. Virtual memory allows ____________
a) execution of a process that may not be completely in memory
b) a program to be smaller than the physical memory
c) a program to be larger than the secondary storage
d) execution of a process without being in physical memory

Answer: a

2. The instruction being executed, must be in ____________
a) physical memory
b) logical memory
c) physical & logical memory
d) none of the mentioned

Answer: a

3. Error handler codes, to handle unusual errors are ____________
a) almost never executed
b) executed very often
c) executed periodically
d) none of the mentioned

Answer: a

4. The ability to execute a program that is only partially in memory has benefits like ____________
a) The amount of physical memory cannot put a constraint on the program
b) Programs for an extremely large virtual space can be created
c) Throughput increases
d) All of the mentioned

Answer: d

5. In virtual memory. the programmer __________ of overlays.
a) has to take care
b) does not have to take care
c) all of the mentioned
d) none of the mentioned

Answer: b

6. Virtual memory is normally implemented by ________
a) demand paging
b) buses
c) virtualization
d) all of the mentioned

Answer: a
Clarification: None.

7. Segment replacement algorithms are more complex than page replacement algorithms because ____________
a) Segments are better than pages
b) Pages are better than segments
c) Segments have variable sizes
d) Segments have fixed sizes

Answer: c
Clarification: None.

8. A swapper manipulates ___________ whereas the pager is concerned with individual _______ of a process.
a) the entire process, parts
b) all the pages of a process, segments
c) the entire process, pages
d) none of the mentioned

Answer: c
Clarification: None.

9. Using a pager ____________
a) increases the swap time
b) decreases the swap time
c) decreases the swap time & amount of physical memory needed
d) increases the amount of physical memory needed

Answer: c
Clarification: None.

10. The valid – invalid bit, in this case, when valid indicates?
a) the page is not legal
b) the page is illegal
c) the page is in memory
d) the page is not in memory

Answer: c
Clarification: None.

11. A page fault occurs when?
a) a page gives inconsistent data
b) a page cannot be accessed due to its absence from memory
c) a page is invisible
d) all of the mentioned

Answer: b
Clarification: None.

12. When a page fault occurs, the state of the interrupted process is ____________
a) disrupted
b) invalid
c) saved
d) none of the mentioned

Answer: c
Clarification: None.

13. When a process begins execution with no pages in memory?
a) process execution becomes impossible
b) a page fault occurs for every page brought into memory
c) process causes system crash
d) none of the mentioned

Answer: b
Clarification: None.

14. If the memory access time is denoted by ‘ma’ and ‘p’ is the probability of a page fault (0 <= p <= 1). Then the effective access time for a demand paged memory is ____________
a) p x ma + (1-p) x page fault time
b) ma + page fault time
c) (1-p) x ma + p x page fault time
d) none of the mentioned

Answer: c
Clarification: None.

15. When the page fault rate is low ____________
a) the turnaround time increases
b) the effective access time increases
c) the effective access time decreases
d) turnaround time & effective access time increases

Answer: c
Clarification: None.

16. Locality of reference implies that the page reference being made by a process ____________
a) will always be to the page used in the previous page reference
b) is likely to be one of the pages used in the last few page references
c) will always be one of the pages existing in memory
d) will always lead to page faults

Answer: b

Operating System Multiple Choice Questions on “File System Implementation – Performance”.

1. _______ tend to represent a major bottleneck in system performance.
a) CPUs
b) Disks
c) Programs
d) I/O

Answer: b

2. In UNIX, even an ’empty’ disk has a percentage of its space lost to ______
a) programs
b) inodes
c) virtual memory
d) stacks

Answer: b

3. By preallocating the inodes and spreading them across the volume, we ___________ the system performance.
a) improve
b) decrease
c) maintain
d) do not affect

Answer: a

4. ____________ writes occur in the order in which the disk subsystem receives them, and the writes are not buffered.
a) Asynchronous
b) Regular
c) Synchronous
d) Irregular

Answer: c

5. In ___________ writes, the data is stored in the cache.
a) Asynchronous
b) Regular
c) Synchronous
d) Irregular

Answer: a

6. A file being read or written sequentially should not have its pages replaced in LRU order, because _____________
a) it is very costly
b) the most recently used page will be used last
c) it is not efficient
d) all of the mentioned

Answer: b
Clarification: None.

7. In the optimized technique for sequential access ___________ removes a page from the buffer as soon as the next page is requested.
a) write ahead
b) read ahead
c) free-behind
d) add-front

Answer: c
Clarification: None.

8. With _______ a requested page and several subsequent pages are read and cached.
a) write ahead
b) read ahead
c) free-behind
d) add-front

Answer: b

Tough Operating System Questions and Answers on “Protection – Revocation of Access Rights”.

1. What are the incorrect methods of revocation of access rights?
a) Immediate/Delayed
b) Selective/General
c) Partial/total
d) Crucial

Answer: d
Clarification: None.

2. Why is it difficult to revoke capabilities?
a) They are too many
b) They are not defined precicely
c) They are distributed throughout the system
d) None of the mentioned

Answer: c
Clarification: None.

3. What is the reacquisition scheme to revoke capability?
a) When a process capability is revoked then it won’t be able to reacquire it
b) Pointers are maintained for each object which can be used to revoke
c) Indirect pointing is done to revoke object’s capabilities
d) Master key can be used compare and revoke.

Answer: a
Clarification: None.

4. What is false regarding Back-Pointers scheme to revoke capability?
a) List of pointers is maintained with each object
b) When revocation is required these pointers are followed
c) This scheme is not adopted in MULTICS system
d) These point to all capabilities associated with that object

Answer: c
Clarification: None.

5. What is true about Indirection to revoke capability?
a) Capabilities point indirectly to the objects
b) Each capability will not have a unique entry in global
c) Table entries cannot be reused for other capabilities
d) This system was adopted in MULTICS system

Answer: a
Clarification: None.

6. How can Keys be defined or replaced?
a) create [keyname] [bits]
b) set-key
c) Key
d) MAKE [Key Name]

Answer: b
Clarification: None.

7. What are the characteristics of the Hydra system?
a) It consists of known access rights and interpreted by the system
b) A user can of protection system can declare other rights
c) Hydra system is not flexible
d) Hydra doesn’t provide rights amplification

Answer: a
Clarification: None.

8. What are the characteristics of rights amplification in Hydra?
a) This scheme allows a procedure to be certified as trustworthy
b) Amplification of rights cannot be stated explicitly in declaration
c) It includes kernel rights such as read
d) All of the mentioned

Answer: a
Clarification: None.

9. What is the problem of mutually suspicious subsystem?
a) Service program can steal users data
b) Service program can malfunction and retain some rights of data provided by user
c) Calling program can get access to restricted portion from service program
d) Calling program gets unrestricted access

Answer: b
Clarification: Both calling program and service program are vulnerable to access each others private data/rights.

10. What are the characteristics of Cambridge CAP system as compared to Hydra system?
a) It is simpler and less powerful than hydra system
b) It is more powerful than hydra system
c) It is powerful than hydra system
d) It is not as secure as Hydra system

Answer: a
Clarification: None.

11. What are the two capabilities defined in CAP system?
a) data & software capability
b) address & data capability
c) hardware & software capability
d) software capability

Answer: a
Clarification: None.

Operating System Multiple Choice Questions on “Semaphores”.

1. An un-interruptible unit is known as ____________
a) single
b) atomic
c) static
d) none of the mentioned

Answer: b
Clarification: None.

2. TestAndSet instruction is executed ____________
a) after a particular process
b) periodically
c) atomically
d) none of the mentioned

Answer: c
Clarification: None.

3. Semaphore is a/an _______ to solve the critical section problem.
a) hardware for a system
b) special program for a system
c) integer variable
d) none of the mentioned

Answer: c
Clarification: None.

4. What are the two atomic operations permissible on semaphores?
a) wait
b) stop
c) hold
d) none of the mentioned

Answer: a
Clarification: None.

5. What are Spinlocks?
a) CPU cycles wasting locks over critical sections of programs
b) Locks that avoid time wastage in context switches
c) Locks that work better on multiprocessor systems
d) All of the mentioned

Answer: d
Clarification: None.

6. What is the main disadvantage of spinlocks?
a) they are not sufficient for many process
b) they require busy waiting
c) they are unreliable sometimes
d) they are too complex for programmers

Answer: b
Clarification: None.

7. The wait operation of the semaphore basically works on the basic _______ system call.
a) stop()
b) block()
c) hold()
d) wait()

Answer: b
Clarification: None.

8. The signal operation of the semaphore basically works on the basic _______ system call.
a) continue()
b) wakeup()
c) getup()
d) start()

Answer: b
Clarification: None.

9. If the semaphore value is negative ____________
a) its magnitude is the number of processes waiting on that semaphore
b) it is invalid
c) no operation can be further performed on it until the signal operation is performed on it
d) none of the mentioned

Answer: a
Clarification: None.

10. The code that changes the value of the semaphore is ____________
a) remainder section code
b) non – critical section code
c) critical section code
d) none of the mentioned

Answer: c
Clarification: None.

11. The following program consists of 3 concurrent processes and 3 binary semaphores. The semaphores are initialized as S0 = 1, S1 = 0, S2 = 0.

Process P0
while(true)
{
    wait(S0);
    print '0';
    release(S1);
    release(S2);
}
 
Process P1
wait(S1);
release(S0);
 
Process P2
wait(S2);
release(S0);

How many times will P0 print ‘0’?
a) At least twice
b) Exactly twice
c) Exactly thrice
d) Exactly once

Answer: a
Clarification: None.

12. Each process Pi, i = 0,1,2,3,……,9 is coded as follows.

repeat
 P(mutex)
 {Critical Section}
 V(mutex)
 forever

The code for P10 is identical except that it uses V(mutex) instead of P(mutex). What is the largest number of processes that can be inside the critical section at any moment (the mutex being initialized to 1)?
a) 1
b) 2
c) 3
d) None of the mentioned

Answer: c
Clarification: Any one of the 9 processes can get into critical section after executing P(mutex) which decrements the mutex value to 0. At this time P10 can enter critical section by incrementing the value to 1. Now any of the 9 processes can enter the critical section by again decrementing the mutex value to 0. None of the remaining processes can get into their critical sections.

13. Two processes, P1 and P2, need to access a critical section of code. Consider the following synchronization construct used by the processes.

Process P1 :
while(true)
{
w1 = true;
while(w2 == true);
Critical section
w1 = false;
}
Remainder Section
 
Process P2 :
while(true)
{
w2 = true;
while(w1 == true);
Critical section
w2 = false;
}
Remainder Section

Here, w1 and w2 have shared variables, which are initialized to false. Which one of the following statements is TRUE about the above construct?
a) It does not ensure mutual exclusion
b) It does not ensure bounded waiting
c) It requires that processes enter the critical section in strict alternation
d) It does not prevent deadlocks but ensures mutual exclusion

Answer: d