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MCQs on Operating System: Part 1 (in Hindi)
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This course discusses some Important MCQs on Operating System for GATE 2018 examination.

Sweta Kumari
YouTuber (channel : GATE NoteBook) | Verified Educator | 2+ year Online Teaching Experience

Unacademy user
Sir, Why Brahamans killed bulls ? Reason.
mam...please provide info about DMap,DLocate,DTrace and DAdd
hi...mam i m a cse student and i m preparing for leet(lateral entry in eng..) so i m have huge request plz make a vedio for that
maa'm.i just wanted to say that this course of yours is very good but i feel you should make a change into it,o feel you should not show the answers at starting,instead give some seconds to us to think about and then you can show the answers as well as explain's just a suggestion if you like it.
Sweta Kumari
3 months ago
COMPLETELY understand
maam in the second question explanation u told printf and scanf are system calls.... but they are C library functions which internally call the write and read system calls of the os.... please correct me if I'm wrong....
Sweta Kumari
5 months ago
printf() actually uses write() system call. The write() system call is actually responsible for sending data to the output. And you are right
Jyotsna G
5 months ago
thank you maam
Hariom Kumar
a day ago
Sweta Kumari
10 months ago
used for monitoring or collecting data about network activity.

  2. 1.What is operating system? a) collection of programs that manages hardware resource:s b) system service provider to the application programs c) link to interface the hardware and application programs d) all of the mentioned Answer:d 2. To access the services of operating system, the interface is provided by the a) system calls b) API c) library d) assembly instructions Answer:a 3. Which one of the following is not true? a) kernel is the program that constitutes the central core of the operating system b) kernel is the first part of operating system to load into memory during booting c) kernel is made of various modules which can not be loaded in running operating system d) kernel remains in the memory during the entire computer session Answer:c

  3. 4. Which one of the following error will be handle by the operating system? a) power failure b) lack of paper in printer c) connection failure in the network d) all of the mentioned Answer:d 5. The main function of the command interpreter is a) to get and execute the next user-specified command b) to provide the interface between the APl and application program c) to handle the files in operating system d) none of the mentioned Answer:a

  4. 6. By operating system, the resource management can be done via a) time division multiplexing b) space division multiplexing c) both (a) and (b) d) none of the mentioned Answer:c 7. If a process fails, most operating system write the error information to a a) log file b) another running process c) new file d) none of the mentioned Answer:a 8. Which facility dynamically adds probes to a running system, both in user processes and in the kernel? a) DTrace b) DLocate c) DMap d) DAdd Answer:a

  5. 9. Which one of the following is not a real time operating system? a) VxWorks b) Windows CE c) RTLinux d) Palm OS Answer:cd 10. The OS X has a) monolithic kernel b) hybrid kernel c) microkernel d) monolithic kernel with modules Answer:b

  6. 1. The systems which allows only one process execution at a time, are called a) uniprogramming systems b) uniprocessing systems c) unitasking systems d) none of the mentioned Answer:b Explanation: Those systems which allows more than one procesS execution at a time, are called multiprogramming systems. Uniprocessing means only one processor. 2. In operating system, each process has its own a) address space and global variables b) open files c) pending alarms, signals and signal handlers d) all of the mentioned Answer:d 3. In Unix, Which system call creates the new process? a) fork b) create c) new d) none of the mentioned Answer:a

  7. 4. A process can be terminated due to a) normal exit b) fatal error c) killed by another process d) all of the mentioned Answer:d 5. What is the ready state of a process? a) when process is scheduled to run after some execution b) when process is unable to run until some task has been com pleted c) when process is using the CPU d) none of the m entioned Answer:a Explanation: When process is unable to run until some task has been completed, the process is in blocked state and if process is using the CPU, it is in running state. 6. What is interprocess communication? a) communication within the process b) communication between two process c) communication between two threads of same process d) none of the m entioned Answer:b

  8. 7. A set of processes is deadlock if a) each process is blocked and will remain so forever b) each process is terminated c) all processes are trying to kill each other d) none of the m entioned Answer:a 8. A process stack does not contain a) function parameters b) local variables c) return addresses d) PID of child process Answer:d 9. Which system call returns the process identifier of a terminated child? a) wait b) exit c) fork d) get Answer:a

  9. 10. The address of the next instruction to be executed by the current process is provided by the a) CPU registers b) program counter c) process stack d) pipe Answer:b

  10. 1. Which process can be affected by other processes executing in the system? a) cooperating process b) child process c) parent process d) init process Answer:a 2. When several processes access the same data concurrently and the outcome of the execution depends on the particular order in which the access takes place, is called a) dynamic condition b) race conditiorn c) essential condition d) critical condition Answer:b 3. If a process is executing in its critical section, then no other processes can be executing in their critical section. This condition is called a) mutual exclusion b) critical exclusion c) synchronous exclusion d) asynchronous exclusion Answer:a

  11. 10. To enable a process to wait within the monitor, a) a condition variable must be declared as condition b) condition variables must be used as boolean objects c) semaphore must be used d) all of the mentioned Answer:a

  12. 1. CPU fetches the instruction from memory according to the value of a) program counter b) status register c) instruction register d) program status word Answer:a 2. A memory buffer used to accommodate a speed differential is called a) stack pointer b) cache c) accumulator d) disk buffer Answer:b 3. Which one of the following is the address generated by CPU? a) physical addres:s b) absolute address c) logical address d) none of the mentioned Answer:C

  13. 10. Operating System maintains the page table for a) each process b) each thread c) each instruction d) each address Answer:a

  14. 7) Transient operating system code is code that: a) is not easily accessible b) comes and goes as needed c) stays in the memory always d) never enters the memory space Answer: b the size of the operating 8) Using transient code, system during program execution a) increases b) decreases c) changes d) maintains Answer: c 9) When memory is divided into several fixed sized partitions, each partition may contain a) exactly one process b) atleast one process c) multiple processes at once d) None of these Answer: a

  15. 10) In fixed sized partition, the degree of multiprogramming is bounded by a) the number of partitions b) the CPU utilization c) the memory size d) All of these Answer: a Explanation: None 11) The first fit, best fit and worst fit are strategies to select a a) process from a queue to put in memory b) processor to run the next process c) free hole from a set of available holes d) All of these Answer: c

  16. 10) When the memory allocated to a process is slightly larger than the process, then: a) internal fragmentation occurs b) external fragmentation occurs c) both a and b d) neither a nor b Answer: a

  17. 1) Physical memory is broken into fixed-sized blocks called a) frames b) pages c) backing store d) None of these 2) Logical memory is broken into blocks of the same size called a) frames b) pages c) backing store d) None of these 3) Every address generated by the CPU is divided into two parts: (choose two) a) frame bit b) page number c) page offset d) frame offset 4) The a) frame bit b) page number c) page offset d) frame offset is used as an index into the page table.

  18. 5) The physical memory a) process b) memory c) page d) frame table contains the base address of each page in 6) The size of a page is typically: a) varied b) power of 2 c) power of 4 d) None of these 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 and the a) m, n b) n, m c) mn, m d) m - n, n bits of a logical address designate the page number, low order bits designate the page offset. fragmentation 8) With paging there is no a) internal b) external c) either type ot d) None of these

  19. s atable that keeps 9) The operating system m aintain 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 10) Paging increases the a) waiting b) execution c) context - switch d) All of these time. 11) Smaller page tables are implemented as a set of a) queues b) stack:s c) counters d) registers 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 these

  20. 1) Each entry in a Translation look-aside buffer (TLB) consists of a) key b) value c) bit value d) constant Answer: a and b 2) If a page number is not found in the TLB, then it is known as a a) TLB miss b) buffer miss c) TLB hit d) TLB hit Answer: a uniquely identifies processes and is used to provide 3) An address space protection for that process. a) address space locator b) address space identifier c) address process identifier d) None of these Answer: b

  21. 7) Illegal addresses are trapped using the__bit. a) error b) protection c) valid invalid d) access Answer: C 8) When there is a large logical address space, the best way of paging would be a) not to page b) a two level paging algorithm c) to page the page table itself d) All of these Answer: b and c

  22. 4) The segment base contains the a) starting logical address of the process b) starting physical address of the segment in memory c) segment length d) None of these Answer: b 5) The segment limit contains the: a) starting logical address of the process b) starting physical address of the segment in memory c) segment length d) None of these Answer: c 6) The offset 'd' of the logical address must be a) greater than segment limit b) between 0 and segment limit c) between 0 and the segment number d) greater than the segment number Answer: b

  23. 7) If the offset is legal: a) it is used as a physical memory address itself b) it is subtracted from the segment base to produce the physical memory address c) it is added to the segment base to produce the physical memory addresS d) None of these Answer: a 8) When the entries in the segment tables of two different processes point to the same physical location: a) the segments are invalid b) the processes get blocked c) segments are shared d) All of these Answer c 9) The protection bit is 0/1 based on: (choose all that apply) a) write only b) read only c) read - write d) None of these Answer: b and c

  24. 10) If there are 32 segments, each of size 1 Kb, then the logical address should have: a) 13 bits b) 14 bits c) 15 bits d) 16 bits Answer: a Explanation: To specify a particular segment, 5 bits are required To select a particular byte after selecting a page, 10 more bits are required. Hence 15 bits are required. 12) A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because: a) it reduces the memory access time to read or write a memory location b) it helps to reduce the size of page table needed to implement the virtual address space of a process c) it is required by the translation look aside buffer d) it helps to reduce the number of page faults in page replacement algorithms Answer: b

  25. 5) A port, a bus, or a device a) controller b) driver c) host d) bus is a collection of electronics that can operate a Answer : a 6) An l/O port typically consists of four registers status, control, and registers. a) system in, system out b) data in, data out c) flow in, flow out d) input, output Answer : b 7) The a) flow in b) flow out c) data in d) data out register is read by the host to get input. Answer c

  26. 8) The a) status b) control c) data in d) data out register is written by the host to send output. Answer d 9) The hardware mechanism that allows a device to notify the CPU is called a) polling b) interrupt c) driver d) controlling Answer b 10) The CPU hardware has a wire called CPU senses after executing every instruction a) interrupt request line b) interrupt bus c) interrupt receive line d) interrupt sense line that the Answer : a

  27. 10) In polling: a) busy - wait cycles wait for I/O from device b) interrupt handler receives interrupts c) interrupt-request line is triggered by I/O device d) All of these Answer a 11) A non blocking system call a) halts the execution of the application for an extended time b) does not halt the execution of the application c) does not block the interrupts d) None of these Answer : b 12) An asynchronous call a) returns immediately, without waiting for the I/O to complete b) does not return immediately and waits for the l/O to complete c) consumes a lot of time d) is too slow Answer a

  28. 1) Buffering is done to a) cope with device speed mismatch b) cope with device transfer size mismatch c) maintain copy semantics d) All of these Answer : d 2) Caching is a) same as b) not the same as c) None of these spooling. Answer : b 3) Caching: (choose all that apply) a) holds a copy of the data b) is fast memory c) holds the only copy of the data d) holds output for a device Answer: a andb

  29. 10) If the number of cy cles spent busy waiting is not excessive, then a) interrupt driven I/O is more efficient than programmed I/O b) programmed I/O is more efficient than interrupt driven I/O c) Both programmed and interrupt driven I/O are equally efficient d) None of these Answer : b

  30. 7. In FIFO page replacement algorithm, when a page must be replaced a) oldest page is chosen b) newest page is chosen c) random page is chosen d) none of the mentioned Answer:a 8. Which algorithm chooses the page that has not been used for the longest period of time whenever the page required to be replaced? a) first in first out algorithm b) additional reference bit algorithm c) least recently used algorithm d) counting based page replacem ent algorithm Answer:c 9. A process is thrashing if a) it is spending more time paging than executing b) it is spending less time paging than executing c) page fault occurs d) swapping can not take place Answer:a

  31. 1) Virtual memory allows a) execution of a process that may not be completely in memory b) a program to be larger 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 and b 2) The instruction being executed, must be in: a) physical memory b) logical memory c) None of these 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 these Answer: a

  32. 4) The ability to execute a program that is only partially in memory has benefits like : (choose all that apply) 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) CPU utilization decreases d) Throughput increases e) response tim e is not affected f) turnaround time increases g) less I/O will be needed to load or swap each user program in memory h) All of these Answer: a, b, d, e, g 5) In virtual memory. the programmerof overlays. a) has to take care b) does not have to take care c) None of these Answer: b

  33. 6) Virtual memory is normally implemented by a) demand paging b) buses c) virtualization d) All of these Answer a 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 whereas the pager is 8) A swapper manipulates concerned with individual a) the entire process, parts b) all the pages of a process, segments c) the entire process, pages d) None of these of a process. Answer: c

  34. 1) Which of the following page replacement algorithms suffers from Belady's Anom aly? a) Optimal replacement b) LRU c) FIFO d) Both optimal replacement and FIFO Answer c 2) 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: b) 10 d) 7 Answer: c 3) In question 2, if the number of page frames is increased to 4, then the number of page transfers: a) decreases b) increases c) rem ains the same d) None of these Answer: b

  35. 12) Optimal page replacem ent algorithm is difficult to implem ent, 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: b 13) 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 these Answer: b

  36. 1) 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: a Explanation: Whenever a reference to a page is made, the contents of the clock register are copied into the time-of-use field in the page-table entry for that page. In this way we always have the time of the last reference to each page. 2) 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 top 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: a and b

  37. 5) 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: C 6) 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: b 7) The minimum number of page fram es that must be allocated to a running process in a virtual memory environm ent is determined by: a) the instruction set architecture b) page size c) physical memory size d) number of processes in memory Answer: a

  38. 4) 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) b and c Answer: a 5) A program is generally composed of several different localities, which a) may b) must c) do not d) must not overlap Answer: a 7) 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: b

  39. 7. Mapping of file is managed by a) file metadata b) page table c) virtual memory d) file system Answer:a 8. 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:a 9. 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:b

  40. 1. Management of metadata information is done by a) file-organisation module b) logical file system c) basic file system d) application programs Answer:b 2. A file control block contains the inform ation about a) file ownership b) file permissions c) location of file contents d) all of the mentioned Answer:d 3. Which table contains the information about each mounted volum e? a) mount table b) system-wide open-file table c) per-process open-file table d) all of the mentioned Answer:cd

  41. 10. 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:c

  42. 8) The open file table has a/an a) file content b) file permission c) open count d) close count associated with each file. Answer: C Explanation: open count indicates the number of processes that have the file open. 9) The file name is generally split into two parts: a) name b) identifier c) extension d) type Answer: a and c

  43. 3) In the sequential access method, information in the file is processed a) one disk after the other, record access doesnt matter b) one record after the other c) one text document after the other d) None of these Answer: b , on random access devices. 4) Sequential access method a) works well b) doesnt work well c) Both a and b d) None of these Answer: a

  44. 8) The index contains: a) names of all contents of file b) pointers to each page c) pointers to the various blocks d) All of these Answer: C 9) For large files, when the index itself becomes too large to be kept in memory a) index is called b) an index is created for the index file c) secondary index files are created d) All of these Answer: b

  45. 1) To organise file systems on disk,: a) they are split into one or more partitions b) information about files is added to each partition c) they are made on different storage spaces d) All of these Answer: a and b that translates 2) The directory can be viewed as a file names into their directory entries. a) symbol table b) partition c) swap space d) cache Answer: a 3) In the single level directory a) All files are contained in different directories all at the same level b) All files are contained in the same directory c) Depends on the operating system d) None of these Answer: b

  46. 4) In the single level directory a) all directories must have unique names b) all files must have unique names c) all files must have unique owners d) All of these Answer: b 5) In the two level directory structure: a) each user has his/her own user file directory b) the system has its own master file directory c) both a and b d) None of these Answer: c

  47. 6) When a user job starts in a two level directory system, or a user logs in a) the users user file directory is searched b) the system's master file directory is searched c) the master file directory is indexed by user name or account number, and each entry points to the UFD for that user d) All of these Answer: b and c 7) When a user refers to particular file, a) system MFD is searched b) his own UFD is searched c) both MFD and UFD are searched d) every directory is searched Answer: b and c 8) The disadvantage of the two level directory structure is that a) it does not solve the name collision problem b) it solves the name collision problem c) it does not isolate users from one another d) it isolates users from one another Answer d

  48. 10) When keeping a list of all the links/references to a file, and the list is empty, implies that: a) the file has no copies b) the file is deleted c) the file is hidden d) None of these Answer : b 11) When a cycle exists, the reference count maybe non zero, even when it is no longer possible to refer to a directory or file, due to a) the possibility of one hidden reference b) the possibility of two hidden references c) the possibility of self referencing d) None of these Answer : c

  49. 10) In a multilevel directory structure: a) the same previous techniques will be used as in the other structures b) a mechanism for directory protection will have to applied c) the subdirectories do not need protection once the directory is protected d) None of these Answer: b 11) In UNIX, the directory protection is handled the file protectiorn a) different b) similar c) it is not handled at all d) None of these Answer: b 12) Disks are segmented into one or more partitions, each containing a file system or a) left 'raw' b) made into swap space c) made into backup space d) left 'ripe' Answer: a

  50. 1) The three major methods of allocating disk space that are in wide use are: a) contiguous b) linked c) indexed d) hashed Answer: a, b and c 2) In contiguous allocation a) each file must occupy a set of contiguous blocks on the disk b) each file is a linked list of disk blocks c) all the pointers to scattered blocks are placed together in one location d) None of these Answer: a 3) In linked allocation: a) each file must occupy a set of contiguous blocks on the disk b) each file is a linked list of disk blocks c) all the pointers to scattered blocks are placed together in one location d) None of these Answer : b

  51. 13) If too little space is allocated to a file, a) the file will not work b) there will not be any space for the data, as the FCB takes it all c) the file cannot be extended d) the file cannot be opened Answer : c

  52. 1) A device driver can be thought of as a translator. Its input consists of instructions. a) high level, low level b) low level, high level c) complex, sim ple d) Both a and c commands and output consists of Answer: a 2) The file organization module knows about: a) files b) logical blocks of files c) physical blocks of files d) All of these Answer d 3) Metadata includes: a) all of the file system structure b) contents of files c) Both a and b d) None of these Answer : c

  53. 10) The major disadvantage with linked allocation is that a) internal fragmentation b) external fragmentation c) there is no sequential access d) there is only sequential access Answer : d 11) If a pointer is lost or damaged in a linked allocation: a) the entire file could get damaged b) only a part of the file would be affected c) there would not be any problems d) None of these Answer a 12) FAT stands for a) File Attribute Transport b) File Allocation Table c) Fork At Time d) None of these Answer : b

  54. 7) Indexed allocation a) supports b) does not support c) is not related to d) None of these direct access. Answer : a 8) The pointer overhead of indexed allocation is generally the pointer overhead of linked allocation a) less than b) equal to c) greater than d) keeps varying with Answer: c 9) For any type of access, contiguous allocation requires access to get a disk block. a) only one b) atleast two c) exactly two d) None of these Answer : a Explanation: We can easily keep the initial address of the file in memory and calculate immediately the disk address of the ith block and read it directly