Operating System MCQ (Multiple Choice Questions) - SchoolingAxis

Operating System MCQ (Multiple Choice Questions)

 Que- 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- All of the mentioned        


Que- 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- does not have to take care        


Que- Virtual memory is normally implemented by ________ 

a. demand paging 

b. buses 

c. virtualization 

d. all of the mentioned 


Answer- demand paging        


Que- 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- Segments have variable sizes        


Que- 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- the entire process, pages        


Que- 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- decreases the swap time & amount of physical memory needed        


Que- 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- the page is in memory        


Que- 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- a page cannot be accessed due to its absence from memory        


Que- When a page fault occurs, the state of the interrupted process is : 

a. disrupted 

b. invalid 

c. saved 

d. none of the mentioned 


Answer- saved        


Que- 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- a page fault occurs for every page brought into memory        


Que- 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- (1-p) x ma + p x page fault time        


Que- 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- the effective access time decreases        


Que- 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- is likely to be one of the pages used in the last few page references        


Que- Which of the following page replacement algorithms suffers from Belady's Anomaly ? 

a. Optimal replacement 

b. LRU 

c. FIFO 

d. Both optimal replacement and FIFO 


Answer- FIFO        


Que- A process refers to 5 pages, A, B, C, D, E in the order : A, B, C, D, A, B, E, A, B, C, D, E. If the page replacement algorithm is FIFO, the number of page transfers with an empty internal store of 3 frames is : 

a. 8 

b. 10 

c. 9 

d. 7 


Answer- 9        


Que- In question 2, if the number of page frames is increased to 4, then the number of page transfers : 

a. decreases 

b. increases 

c. remains the same 

d. none of the mentioned 


Answer- increases        


Que- A memory page containing a heavily used variable that was initialized very early and is in constant use is removed, then the page replacement algorithm used is : 

a. LRU 

b. LFU 

c. FIFO 

d. None of the mentioned 


Answer- FIFO        


Que- A virtual memory system uses First In First Out (FIFO) page replacement policy and allocates a fixed number of frames to a process. Consider the following statements : P : Increasing the number of page frames allocated to a process sometimes increases the page fault rate Q : Some programs do not exhibit locality of referenceWhich of the following is TRUE? 

a. Both P and Q are true, and Q is the reason for P 

b. Both P and Q are true, but Q is not the reason for P 

c. P is false but Q is true 

d. Both P and Q are false 


Answer- P is false but Q is true        


Que- Users _______ that their processes are running on a paged system. 

a. are aware 

b. are unaware 

c. may unaware 

d. none of the mentioned 


Answer- are unaware        


Que- If no frames are free, _____ page transfer(s) is/are required. 

a. one 

b. two 

c. three 

d. four 


Answer- two        


Que- When a page is selected for replacement, and its modify bit is set : 

a. the page is clean 

b. the page has been modified since it was read in from the disk 

c. the page is dirty 

d. the page has been modified since it was read in from the disk & page is dirty 


Answer- the page has been modified since it was read in from the disk & page is dirty        


Que- The aim of creating page replacement algorithms is to : 

a. replace pages faster 

b. increase the page fault rate 

c. decrease the page fault rate 

d. to allocate multiple pages to processes 


Answer- decrease the page fault rate        


Que- A FIFO replacement algorithm associates with each page the _______ 

a. time it was brought into memory 

b. size of the page in memory 

c. page after and before it 

d. all of the mentioned 


Answer- time it was brought into memory        


Que- Optimal page - replacement algorithm is : 

a. Replace the page that has not been used for a long time 

b. Replace the page that has been used for a long time 

c. Replace the page that will not be used for a long time 

d. None of the mentioned 


Answer- Replace the page that will not be used for a long time        


Que- Optimal page - replacement algorithm is difficult to implement, because : 

a. it requires a lot of information 

b. it requires future knowledge of the reference string 

c. it is too complex 

d. it is extremely expensive 


Answer- it requires future knowledge of the reference string        


Que- LRU page - replacement algorithm associates with each page the ______ 

a. time it was brought into memory 

b. the time of that page's last use 

c. page after and before it 

d. all of the mentioned 


Answer- the time of that page's last use        


Que- For 3 page frames, the following is the reference string : 7 0 1 2 0 3 0 4 2 3 0 3 2 1 2 0 1 7 0 1How many page faults does the LRU page replacement algorithm produce ? 

a. 10 

b. 15 

c. 11 

d. 12 


Answer- 12        


Que- The two methods how LRU page replacement policy can be implemented in hardware are: 

a. Counters 

b. RAM & Registers 

c. Stack & Counters 

d. Registers 


Answer- Stack & Counters        


Que- When using counters to implement LRU, we replace the page with the : 

a. smallest time value 

b. largest time value 

c. greatest size 

d. none of the mentioned 


Answer- smallest time value        


Que- In the stack implementation of the LRU algorithm, a stack can be maintained in a manner : 

a. whenever a page is used, it is removed from the stack and put on bottom 

b. the bottom of the stack is the LRU page 

c. the top of the stack contains the LRU page and all new pages are added to the top 

d. none of the mentioned 


Answer- the bottom of the stack is the LRU page        


Que- There is a set of page replacement algorithms that can never exhibit Belady's Anomaly, called : 

a. queue algorithms 

b. stack algorithms 

c. string algorithms 

d. none of the mentioned 


Answer- stack algorithms        


Que- Increasing the RAM of a computer typically improves performance because: 

a. Virtual memory increases 

b. Larger RAMs are faster 

c. Fewer page faults occur 

d. None of the mentioned 


Answer- Fewer page faults occur        


Que- The essential content(s) in each entry of a page table is / are : 

a. Virtual page number 

b. Page frame number 

c. Both virtual page number and page frame number 

d. Access right information 


Answer- Page frame number        


Que- The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by : 

a. the instruction set architecture 

b. page size 

c. physical memory size 

d. number of processes in memory 


Answer- the instruction set architecture        


Que- The reason for using the LFU page replacement algorithm is : 

a. an actively used page should have a large reference count 

b. a less used page has more chances to be used again 

c. it is extremely efficient and optimal 

d. all of the mentioned 


Answer- an actively used page should have a large reference count        


Que- The reason for using the MFU page replacement algorithm is : 

a. an actively used page should have a large reference count 

b. a less used page has more chances to be used again 

c. it is extremely efficient and optimal 

d. all of the mentioned 


Answer- a less used page has more chances to be used again        


Que- The implementation of the LFU and the MFU algorithm is very uncommon because : 

a. they are too complicated 

b. they are optimal 

c. they are expensive 

d. all of the mentioned 


Answer- they are expensive        


Que- The minimum number of frames to be allocated to a process is decided by the : 

a. the amount of available physical memory 

b. operating System 

c. instruction set architecture 

d. none of the mentioned 


Answer- instruction set architecture        


Que- When a page fault occurs before an executing instruction is complete : 

a. the instruction must be restarted 

b. the instruction must be ignored 

c. the instruction must be completed ignoring the page fault 

d. none of the mentioned 


Answer- the instruction must be restarted        


Que- Consider a machine in which all memory reference instructions have only one memory address, for them we need at least _____ frame(s). 

a. one 

b. two 

c. three 

d. none of the mentioned 


Answer- two        


Que- The maximum number of frames per process is defined by : 

a. the amount of available physical memory 

b. operating System 

c. instruction set architecture 

d. none of the mentioned 


Answer- the amount of available physical memory        


Que- The algorithm in which we split m frames among n processes, to give everyone an equal share, m/n frames is known as : 

a. proportional allocation algorithm 

b. equal allocation algorithm 

c. split allocation algorithm 

d. none of the mentioned 


Answer- equal allocation algorithm        


Que- The algorithm in which we allocate memory to each process according to its size is known as : 

a. proportional allocation algorithm 

b. equal allocation algorithm 

c. split allocation algorithm 

d. none of the mentioned 


Answer- proportional allocation algorithm        


Que- With either equal or proportional algorithm, a high priority process is treated ___________ a low priority process. 

a. greater than 

b. same as 

c. lesser than 

d. none of the mentioned 


Answer- same as        


Que- _________ replacement allows a process to select a replacement frame from the set of all frames, even if the frame is currently allocated to some other process. 

a. Local 

b. Universal 

c. Global 

d. Public 


Answer- Global        


Que- _________ replacement allows each process to only select from its own set of allocated frames. 

a. Local 

b. Universal 

c. Global 

d. Public 


Answer- Local        


Que- One problem with the global replacement algorithm is that : 

a. it is very expensive 

b. many frames can be allocated to a process 

c. only a few frames can be allocated to a process 

d. a process cannot control its own page - fault rate 


Answer- a process cannot control its own page - fault rate        


Que- ________ replacement generally results in greater system throughput. 

a. Local 

b. Global 

c. Universal 

d. Public 


Answer- Global        


Que- A process is thrashing if : 

a. it spends a lot of time executing, rather than paging 

b. it spends a lot of time paging, than executing 

c. it has no memory allocated to it 

d. none of the mentioned 


Answer- it spends a lot of time paging, than executing        


Que- Thrashing _______ the CPU utilization. 

a. increases 

b. keeps constant 

c. decreases 

d. none of the mentioned 


Answer- decreases        


Que- A locality is : 

a. a set of pages that are actively used together 

b. a space in memory 

c. an area near a set of processes 

d. none of the mentioned 


Answer- a set of pages that are actively used together        


Que- When a subroutine is called, 

a. it defines a new locality 

b. it is in the same locality from where it was called 

c. it does not define a new locality 

d. none of the mentioned 


Answer- it defines a new locality        


Que- A program is generally composed of several different localities, which _____ overlap. 

a. may 

b. must 

c. do not 

d. must not 


Answer- may        


Que- In the working set model, for :2 6 1 5 7 7 7 7 5 1 6 2 3 4 1 2 3 4 4 4 3 4 3 4 4 4 1 3 2 3if DELTA = 10, then the working set at time t1 (?Ǫ.7 5 1) is : 

a. {1, 2, 4, 5, 6} 

b. {2, 1, 6, 7, 3} 

c. {1, 6, 5, 7, 2} 

d. {1, 2, 3, 4, 5} 


Answer- {1, 6, 5, 7, 2}        


Que- The accuracy of the working set depends on the selection of : 

a. working set model 

b. working set size 

c. memory size 

d. number of pages in memory 


Answer- working set size        


Que- If working set window is too small : 

a. it will not encompass entire locality 

b. it may overlap several localities 

c. it will cause memory problems 

d. none of the mentioned 


Answer- it will not encompass entire locality        


Que- If working set window is too large : 

a. it will not encompass entire locality 

b. it may overlap several localities 

c. it will cause memory problems 

d. none of the mentioned 


Answer- it may overlap several localities        


Que- If the sum of the working - set sizes increases, exceeding the total number of available frames : 

a. then the process crashes 

b. the memory overflows 

c. the system crashes 

d. the operating system selects a process to suspend 


Answer- the operating system selects a process to suspend        


Que- Consider the following page reference string :1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6 For LRU page replacement algorithm with 4 frames, the number of page faults is : 

a. 10 

b. 14 

c. 8 

d. 11 


Answer- 10        


Que- Consider the following page reference string :1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6 For LRU page replacement algorithm with 5 frames, the number of page faults is : 

a. 10 

b. 14 

c. 8 

d. 11 


Answer- 8        


Que- Consider the following page reference string :1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6 For FIFO page replacement algorithms with 3 frames, the number of page faults is : 

a. 16 

b. 15 

c. 14 

d. 11 


Answer- 16        


Que- Consider the following page reference string :1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6 For FIFO page replacement algorithms with 4 frames, the number of page faults is : 

a. 16 

b. 15 

c. 14 

d. 11 


Answer- 14        


Que- Consider the following page reference string :1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6 For Optimal page replacement algorithms with 3 frames, the number of page faults is : 

a. 16 

b. 15 

c. 14 

d. 11 


Answer- 11        


Que- ______ is a unique tag, usually a number, identifies the file within the file system. 

a. File identifier 

b. File name 

c. File type 

d. None of the mentioned  


Answer- File identifier        


Que- To create a file 

a. allocate the space in file system 

b. make an entry for new file in directory 

c. allocate the space in file system & make an entry for new file in directory 

d. none of the mentioned  


Answer- allocate the space in file system & make an entry for new file in directory        


Que- By using the specific system call, we can 

a. open the file 

b. read the file 

c. write into the file 

d. all of the mentioned  


Answer- all of the mentioned         


Que- File type can be represented by 

a. file name 

b. file extension 

c. file identifier 

d. none of the mentioned  


Answer- file extension        


Que- Which file is a sequence of bytes organized into blocks understandable by the system's linker? 

a. object file 

b. source file 

c. executable file 

d. text file  


Answer- object file        


Que- What is the mounting of file system? 

a. crating of a filesystem 

b. deleting a filesystem 

c. attaching portion of the file system into a directory structure 

d. removing portion of the file system into a directory structure  


Answer- attaching portion of the file system into a directory structure        


Que- Mapping of file is managed by 

a. file metadata 

b. page table 

c. virtual memory 

d. file system  


Answer- file metadata        


Que- Mapping of network file system protocol to local file system is done by 

a. network file system 

b. local file system 

c. volume manager 

d. remote mirror  


Answer- network file system        


Que- Which one of the following explains the sequential file access method? 

a. random access according to the given byte number 

b. read bytes one at a time, in order 

c. read/write sequentially by record 

d. read/write randomly by record  


Answer- read bytes one at a time, in order        


Que- file system fragmentation occurs when 

a. unused space or single file are not contiguous 

b. used space is not contiguous 

c. unused space is non-contiguous 

d. multiple files are non-contiguous  


Answer- unused space or single file are not contiguous        


Que- Management of metadata information is done by 

a. file-organisation module 

b. logical file system 

c. basic file system 

d. application programs  


Answer- logical file system        


Que- A file control block contains the information about 

a. file ownership 

b. file permissions 

c. location of file contents 

d. all of the mentioned  


Answer- all of the mentioned         


Que- Which table contains the information about each mounted volume? 

a. mount table 

b. system-wide open-file table 

c. per-process open-file table 

d. all of the mentioned  


Answer- all of the mentioned         


Que- To create a new file application program calls 

a. basic file system 

b. logical file system 

c. file-organisation module 

d. none of the mentioned  


Answer- logical file system        


Que- When a process closes the file 

a. per-process table entry is not removed 

b. system wide entry's open count is decremented 

c. all of the mentioned 

d. none of the mentioned  


Answer- system wide entry's open count is decremented        


Que- What is raw disk? 

a. disk without file system 

b. empty disk 

c. disk lacking logical file system 

d. disk having file system  


Answer- disk without file system        


Que- The data structure used for file directory is called 

a. mount table 

b. hash table 

c. file table 

d. process table  


Answer- hash table        


Que- In which type of allocation method each file occupy a set of contiguous block on the disk? 

a. contiguous allocation 

b. dynamic-storage allocation 

c. linked allocation 

d. indexed allocation  


Answer- contiguous allocation        


Que- If the block of free-space list is free then bit will 

a. 1 

b. 0 

c. any of 0 or 1 

d. none of the mentioned  


Answer- 1        


Que- Which protocol establishes the initial logical connection between a server and a client? 

a. transmission control protocol 

b. user datagram protocol 

c. mount protocol 

d. datagram congestion control protocol  


Answer- mount protocol        


Que- Data cannot be written to secondary storage unless written within a ______ 

a. file 

b. swap space 

c. directory 

d. text format 


Answer- file        


Que- File attributes consist of : 

a. name 

b. type 

c. identifier 

d. all of the mentioned 


Answer- all of the mentioned        


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