Operating System MCQ (Multiple Choice Questions) - SchoolingAxis

Operating System MCQ (Multiple Choice Questions)

 Que- 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- the most recently used page will be used last        


Que- 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- free-behind        


Que- 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- read ahead        


Que- Some directory information is kept in main memory or cache to ___________ 

a. fill up the cache 

b. increase free space in secondary storage 

c. decrease free space in secondary storage 

d. speed up access 


Answer- speed up access        


Que- A systems program such as fsck in ______ is a consistency checker. 

a. UNIX 

b. Windows 

c. Macintosh 

d. Solaris 


Answer- UNIX        


Que- A consistency checker __________________ and tries to fix any inconsistencies it finds. 

a. compares the data in the secondary storage with the data in the cache 

b. compares the data in the directory structure with the data blocks on disk 

c. compares the system generated output and user required output 

d. all of the mentioned 


Answer- compares the data in the directory structure with the data blocks on disk        


Que- Each set of operations for performing a specific task is a _________ 

a. program 

b. code 

c. transaction 

d. all of the mentioned 


Answer- transaction        


Que- Once the changes are written to the log, they are considered to be ________ 

a. committed 

b. aborted 

c. completed 

d. none of the mentioned 


Answer- committed        


Que- When an entire committed transaction is completed, ___________ 

a. it is stored in the memory 

b. it is removed from the log file 

c. it is redone 

d. none of the mentioned 


Answer- it is removed from the log file        


Que- A circular buffer : 

a. writes to the end of its space and then continues at the beginning 

b. overwrites older values as it goes 

c. all of the mentioned 

d. none of the mentioned 


Answer- writes to the end of its space and then continues at the beginning        


Que- All the changes that were done from a transaction that did not commit before the system crashed, have to be _________ 

a. saved 

b. saved and the transaction redone 

c. undone 

d. none of the mentioned 


Answer- undone        


Que- A machine in Network file system (NFS) can be ________ 

a. client 

b. server 

c. both client and server 

d. neither client nor server 


Answer- both client and server        


Que- A _________ directory is mounted over a directory of a _______ file system. 

a. local, remote 

b. remote, local 

c. local, local 

d. none of the mentioned 


Answer- none of the mentioned        


Que- The _________ becomes the name of the root of the newly mounted directory. 

a. root of the previous directory 

b. local directory 

c. remote directory itself 

d. none of the mentioned 


Answer- local directory        


Que- ___________ mounts, is when a file system can be mounted over another file system, that is remotely mounted, not local. 

a. recursive 

b. cascading 

c. trivial 

d. none of the mentioned 


Answer- cascading        


Que- The mount mechanism ________ a transitive property. 

a. exhibits 

b. does not exhibit 

c. may exhibit 

d. none of the mentioned 


Answer- does not exhibit        


Que- A mount operation includes the : 

a. name of the network 

b. name of the remote directory to be mounted 

c. name of the server machine storing it 

d. all of the mentioned 


Answer- name of the remote directory to be mounted        


Que- The mount request is mapped to the corresponding _____ and is forwarded to the mount server running on the specific server machine. 

a. IPC 

b. System 

c. CPU 

d. RPC 


Answer- System        


Que- The server maintains a/an ________ that specifies local file systems that it exports for mounting, along with names of machines that are permitted to mount them. 

a. export list 

b. import list 

c. sending list 

d. receiving list 


Answer- export list        


Que- In UNIX, the file handle consists of a __________ and __________ 

a. file-system identifier & an inode number 

b. an inode number & FAT 

c. a FAT & an inode number 

d. a file pointer & FAT 


Answer- file-system identifier & an inode number        


Que- The NFS servers : 

a. are stateless 

b. save the current state of the request 

c. maybe stateless 

d. none of the mentioned 


Answer- are stateless        


Que- Every NFS request has a _________ allowing the server to determine if a request is duplicated or if any are missing. 

a. name 

b. transaction 

c. sequence number 

d. all of the mentioned 


Answer- sequence number        


Que- A server crash and recovery will __________ to a client. 

a. be visible 

b. affect 

c. be invisible 

d. harm 


Answer- be invisible        


Que- The server must write all NFS data ___________ 

a. synchronously 

b. asynchronously 

c. index-wise 

d. none of the mentioned 


Answer- synchronously        


Que- A single NFS write procedure : 

a. can be atomic 

b. is atomic 

c. is non atomic 

d. none of the mentioned 


Answer- is atomic        


Que- The NFS protocol, __________ concurrency control mechanisms. 

a. provides 

b. does not provide 

c. may provide 

d. none of the mentioned 


Answer- does not provide        


Que- _______________ in NFS involves the parsing of a path name into separate directory entries - or components. 

a. Path parse 

b. Path name parse 

c. Path name translation 

d. Path name parsing 


Answer- Path name translation        


Que- For every pair of component and directory vnode after path name translation : 

a. a single NFS lookup call is used sequentially 

b. a single NFS lookup call is used beginning from the last component 

c. at least two NFS lookup calls per component are performed 

d. a separate NFS lookup call is performed 


Answer- a separate NFS lookup call is performed        


Que- When a client has a cascading mount, _______ server(s) is/are involved in a path name traversal. 

a. at least one 

b. more than one 

c. more than two 

d. more than three 


Answer- more than one        


Que- I/O hardware contains 

a. Bus 

b. Controller 

c. I/O port and its registers 

d. All of the mentioned  


Answer- All of the mentioned         


Que- The data-in register of I/O port is 

a. Read by host to get input 

b. Read by controller to get input 

c. Written by host to send output 

d. Written by host to start a command  


Answer- Read by host to get input        


Que- The host sets _____ bit when a command is available for the controller to execute. 

a. write 

b. status 

c. command-ready 

d. control  


Answer- command-ready        


Que- When hardware is accessed by reading and writing to the specific memory locations, then it is called 

a. port-mapped I/O 

b. controller-mapped I/O 

c. bus-mapped I/O 

d. none of the mentioned  


Answer- none of the mentioned         


Que- Device drivers are implemented to interface 

a. character devices 

b. block devices 

c. network devices 

d. all of the mentioned  


Answer- all of the mentioned         


Que- Which hardware triggers some operation after certain programmed count? 

a. programmable interval timer 

b. interrupt timer 

c. programmable timer 

d. none of the mentioned  


Answer- programmable interval timer        


Que- The device-status table contains 

a. each I/O device type 

b. each I/O device address 

c. each I/O device state 

d. all of the mentioned  


Answer- all of the mentioned         


Que- Which buffer holds the output for a device? 

a. spool 

b. output 

c. status 

d. magic  


Answer- spool        


Que- Which one of the following connects high-speed high-bandwidth device to memory subsystem and CPU. 

a. Expansion bus 

b. PCI bus 

c. SCSI bus 

d. None of the mentioned  


Answer- Expansion bus        


Que- A process is moved to wait queue when I/O request is made with 

a. non-blocking I/O 

b. blocking I/O 

c. asynchronous I/O 

d. synchronous I/O  


Answer- blocking I/O        


Que- In _______ information is recorded magnetically on platters. 

a. magnetic disks 

b. electrical disks 

c. assemblies 

d. cylinders 


Answer- magnetic disks        


Que- The heads of the magnetic disk are attached to a _____ that moves all the heads as a unit. 

a. spindle 

b. disk arm 

c. track 

d. none of the mentioned 


Answer- disk arm        


Que- The set of tracks that are at one arm position make up a ___________ 

a. magnetic disks 

b. electrical disks 

c. assemblies 

d. cylinders 


Answer- cylinders        


Que- The time taken to move the disk arm to the desired cylinder is called the : 

a. positioning time 

b. random access time 

c. seek time 

d. rotational latency 


Answer- seek time        


Que- The time taken for the desired sector to rotate to the disk head is called : 

a. positioning time 

b. random access time 

c. seek time 

d. rotational latency 


Answer- rotational latency        


Que- When the head damages the magnetic surface, it is known as _________ 

a. disk crash 

b. head crash 

c. magnetic damage 

d. all of the mentioned 


Answer- head crash        


Que- A floppy disk is designed to rotate ___________ as compared to a hard disk drive. 

a. faster 

b. slower 

c. at the same speed 

d. none of the mentioned 


Answer- slower        


Que- The host controller is : 

a. controller built at the end of each disk 

b. controller at the computer end of the bus 

c. all of the mentioned 

d. none of the mentioned 


Answer- controller at the computer end of the bus        


Que- ______ controller sends the command placed into it, via messages to the _____ controller. 

a. host, host 

b. disk, disk 

c. host, disk 

d. disk, host 


Answer- host, disk        


Que- The disk bandwidth is : 

a. the total number of bytes transferred 

b. total time between the first request for service and the completion on the last transfer 

c. the total number of bytes transferred divided by the total time between the first request for service and the completion on the last transfer 

d. none of the mentioned 


Answer- the total number of bytes transferred divided by the total time between the first request for service and the completion on the last transfer        


Que- Whenever a process needs I/O to or from a disk it issues a ______________ 

a. system call to the CPU 

b. system call to the operating system 

c. a special procedure 

d. all of the mentioned 


Answer- system call to the operating system        


Que- If a process needs I/O to or from a disk, and if the drive or controller is busy then : 

a. the request will be placed in the queue of pending requests for that drive 

b. the request will not be processed and will be ignored completely 

c. the request will be not be placed 

d. none of the mentioned 


Answer- the request will be placed in the queue of pending requests for that drive        


Que- Consider a disk queue with requests for I/O to blocks on cylinders : 98 183 37 122 14 124 65 67Considering FCFS (first cum first served) scheduling, the total number of head movements is, if the disk head is initially at 53 : 

a. 600 

b. 620 

c. 630 

d. 640 


Answer- 640        


Que- Consider a disk queue with requests for I/O to blocks on cylinders : 98 183 37 122 14 124 65 67Considering SSTF (shortest seek time first) scheduling, the total number of head movements is, if the disk head is initially at 53 : 

a. 224 

b. 236 

c. 245 

d. 240 


Answer- 236        


Que- Random access in magnetic tapes is _________ compared to magnetic disks. 

a. fast 

b. very fast 

c. slow 

d. very slow 


Answer- very slow        


Que- Magnetic tape drives can write data at a speed ________ disk drives. 

a. much lesser than 

b. comparable to 

c. much faster than 

d. none of the mentioned 


Answer- comparable to        


Que- On media that use constant linear velocity (CLV), the _____________ is uniform. 

a. density of bits on the disk 

b. density of bits per sector 

c. the density of bits per track 

d. none of the mentioned 


Answer- the density of bits per track        


Que- SSTF algorithm, like SJF __________ of some requests. 

a. may cause starvation 

b. will cause starvation 

c. does not cause starvation 

d. causes aging 


Answer- may cause starvation        


Que- In the ______ algorithm, the disk arm starts at one end of the disk and moves toward the other end, servicing requests till the other end of the disk. At the other end, the direction is reversed and servicing continues. 

a. LOOK 

b. SCAN 

c. C-SCAN 

d. C-LOOK 


Answer- SCAN        


Que- In the _______ algorithm, the disk head moves from one end to the other , servicing requests along the way. When the head reaches the other end, it immediately returns to the beginning of the disk without servicing any requests on the return trip. 

a. LOOK 

b. SCAN 

c. C-SCAN 

d. C-LOOK 


Answer- C-SCAN        


Que- In the ______ algorithm, the disk arm goes as far as the final request in each direction, then reverses direction immediately without going to the end of the disk. 

a. LOOK 

b. SCAN 

c. C-SCAN 

d. C-LOOK 


Answer- LOOK        


Que- The process of dividing a disk into sectors that the disk controller can read and write, before a disk can store data is known as : 

a. partitioning 

b. swap space creation 

c. low-level formatting 

d. none of the mentioned 


Answer- low-level formatting        


Que- The data structure for a sector typically contains : 

a. header 

b. data area 

c. trailer 

d. all of the mentioned 


Answer- all of the mentioned        


Que- The header and trailer of a sector contain information used by the disk controller such as _________ and _________ 

a. main section & disk identifier 

b. error correcting codes (ECC) & sector number 

c. sector number & main section 

d. disk identifier & sector number 


Answer- error correcting codes (ECC) & sector number        


Que- The two steps the operating system takes to use a disk to hold its files are _______ and ________ 

a. partitioning & logical formatting 

b. swap space creation & caching 

c. caching & logical formatting 

d. logical formatting & swap space creation 


Answer- partitioning & logical formatting        


Que- 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. main 

b. bootloader 

c. bootstrap 

d. rom 


Answer- bootstrap        


Que- For most computers, the bootstrap is stored in ________ 

a. RAM 

b. ROM 

c. Cache 

d. Tertiary storage 


Answer- ROM        


Que- A disk that has a boot partition is called a _________ 

a. start disk 

b. end disk 

c. boot disk 

d. all of the mentioned 


Answer- boot disk        


Que- Defective sectors on disks are often known as __________ 

a. good blocks 

b. destroyed blocks 

c. bad blocks 

d. none of the mentioned 


Answer- bad blocks        


Que- 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, high level formatting 

b. bad blocks, partitioning 

c. bad blocks, low level formatting 

d. destroyed blocks, partitioning 


Answer- bad blocks, low level formatting        


Que- The scheme used in the above question is known as _______ or ________ 

a. sector sparing & forwarding 

b. forwarding & sector utilization 

c. backwarding & forwarding 

d. sector utilization & backwarding 


Answer- sector sparing & forwarding        


Que- An unrecoverable error is known as _________ 

a. hard error 

b. tough error 

c. soft error 

d. none of the mentioned 


Answer- hard error        


Que- Virtual memory uses disk space as an extension of _________ 

a. secondary storage 

b. main memory 

c. tertiary storage 

d. none of the mentioned 


Answer- main memory        


Que- Using swap space significantly _________ system performance. 

a. increases 

b. decreases 

c. maintains 

d. does not affect 


Answer- decreases        


Que- Linux __________ the use of multiple swap spaces. 

a. allows 

b. does not allow 

c. may allow 

d. none of the mentioned 


Answer- allows        


Que- A single swap space ______ reside in two places. 

a. can 

b. cannot 

c. must not 

d. none of the mentioned 


Answer- can        


Que- If the swap space is simply a large file, within the file system, ____________ used to create it, name it and allocate its space. 

a. special routines must be 

b. normal file system routines can be 

c. normal file system routines cannot be 

d. swap space storage manager is 


Answer- normal file system routines can be        


Que- For swap space created in a separate disk partition where no file system or directory structure is placed, _____________ used to allocate and deallocate the blocks. 

a. special routines must be 

b. normal file system routines can be 

c. normal file system routines cannot be 

d. swap space storage manager is 


Answer- swap space storage manager is        


Que- When a fixed amount of swap space is created during disk partitioning, more swap space can be added only by : (I) repartitioning of the disk (II) adding another swap space elsewhere 

a. only I 

b. only II 

c. both I and II 

d. neither I nor II 


Answer- both I and II        


Que- In UNIX, two per process ________ are used by the kernel to track swap space use. 

a. process tables 

b. swap maps 

c. memory maps 

d. partition maps 


Answer- swap maps        


Que- It is __________ to reread a page from the file system than to write it to swap space and then to reread it from there. 

a. useless 

b. less efficient 

c. more efficient 

d. none of the mentioned 


Answer- more efficient        


Que- RAID level 3 supports a lower number of I/Os per second, because _______________ 

a. Every disk has to participate in every I/O request 

b. Only one disk participates per I/O request 

c. I/O cycle consumes a lot of CPU time 

d. All of the mentioned 


Answer- Every disk has to participate in every I/O request        


Que- RAID level _____ is also known as block interleaved parity organisation and uses block level striping and keeps a parity block on a separate disk. 

a. 1 

b. 2 

c. 3 

d. 4 


Answer- 4        


Que- A performance problem with _________ is the expense of computing and writing parity. 

a. non-parity based RAID levels 

b. parity based RAID levels 

c. all RAID levels 

d. none of the mentioned 


Answer- parity based RAID levels        


Que- In RAID level 4, one block read, accesses __________ 

a. only one disk 

b. all disks simultaneously 

c. all disks sequentially 

d. none of the mentioned 


Answer- only one disk        


Que- The overall I/O rate in RAID level 4 is : 

a. low 

b. very low 

c. high 

d. none of the mentioned 


Answer- high        


Que- A write of a block has to access : 

a. the disk on which the block is stored 

b. parity disk 

c. a parity block 

d. all of the mentioned 


Answer- all of the mentioned        


Que- RAID level 5 is also known as : 

a. bit-interleaved parity organization 

b. block-interleaved parity organization 

c. block-interleaved distributed parity 

d. memory-style ECC organization 


Answer- block-interleaved distributed parity        


Que- RAID level ____ spreads parity and data among all N+1 disks rather than storing data in N disks and parity in 1. 

a. 3 

b. 4 

c. 5 

d. 6 


Answer- 5        


Que- The potential overuse of a single parity disk is avoided in RAID level _______ 

a. 3 

b. 4 

c. 5 

d. all of the mentioned 


Answer- 5        


Que- RAID level 0+1 is used because, RAID level 0 provides ______ whereas RAID level 1 provides ________ 

a. performance, redundancy 

b. performance, reliability 

c. redundancy, performance 

d. none of the mentioned 


Answer- performance, reliability        


Que- If a disk fails in RAID level ___ rebuilding lost data is easiest. 

a. 1 

b. 2 

c. 3 

d. 4 


Answer- 1        


Que- Where performance and reliability are both important, RAID level ____ is used. 

a. 0 

b. 1 

c. 2 

d. 0+1 


Answer- 0+1        


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