Here is the completely updated `question.php`.
I added the missing `$breadcrumbs` array and defined `$category_name` and `$topic_name` right before the header is included. This ensures that `header.php` generates the correct Breadcrumb Schema, page title, and meta description for single question pages.
Replace your entire `question.php` with this:
```php
Operating Systems Questions
Q.
What is the primary function of an operating system?
To manage hardware resources and provide services to applications
To design computer hardware circuits
To manufacture computer processors
To create programming languages exclusively
Explanation:
An operating system manages hardware resources, provides services to applications, and enables users to interact with a computer system.
Q.
Which of the following is an example of an open-source operating system?
Linux
Microsoft Windows
Microsoft Excel
macOS
Explanation:
Linux is an open-source operating system whose source code can be inspected, modified, and distributed under its applicable licenses.
Q.
What is a process in an operating system?
A collection of computer networks
A program in execution
A physical component of the CPU
A file stored permanently on a hard drive
Explanation:
A process is a program in execution, together with its execution state, allocated resources, and associated operating system information.
Q.
Which scheduling algorithm allocates CPU time to processes in fixed time slices?
Priority Scheduling
Round Robin
Shortest Job First
First-Come, First-Served
Explanation:
Round Robin scheduling assigns each ready process a fixed time quantum. If a process does not finish within its quantum, it is moved to the end of the ready queue.
Q.
What is the main purpose of virtual memory?
To prevent all application errors
To increase the physical clock speed of the CPU
To eliminate the need for secondary storage
To provide processes with virtual address spaces and support memory use beyond physical RAM
Explanation:
Virtual memory allows processes to use virtual address spaces that can exceed the available physical RAM by keeping selected data on secondary storage and bringing it into memory when needed.
Q.
Which of the following is a necessary condition for deadlock?
Automatic CPU overclocking
Unlimited resource availability
Guaranteed process termination
Mutual exclusion
Explanation:
Mutual exclusion is one of the four Coffman conditions for deadlock. The other three are hold and wait, no preemption, and circular wait.
Q.
What is a context switch?
The replacement of a computer's operating system
The process of permanently deleting a program
Saving one process's execution state and restoring another's
The conversion of source code into machine code
Explanation:
A context switch occurs when the operating system saves the execution state of one process or thread and restores the state of another so that execution can continue.
Q.
Which memory management technique divides logical memory into fixed-size blocks called pages?
Paging
CPU pipelining
Segmentation only
Disk formatting
Explanation:
Paging divides a process's virtual address space into fixed-size pages and physical memory into corresponding fixed-size frames. Pages can be mapped to available frames without requiring contiguous physical memory.
Q.
What is the primary role of a device driver?
To create user passwords automatically
To enable the operating system to communicate with hardware devices
To compile every application on the computer
To replace the system's file system
Explanation:
A device driver enables the operating system to communicate with and control a particular hardware device through its supported interface.
Q.
Which of the following best describes a thread?
A type of network cable
A permanent storage partition
A unit of execution within a process
A separate physical processor installed on the motherboard
Explanation:
A thread is an execution unit within a process. Threads in the same process typically share its address space and process resources, while maintaining their own execution state and stack.
Q.
What is the main purpose of a semaphore in concurrent programming?
To synchronize processes or threads and coordinate resource access
To accelerate network connections
To translate high-level programming languages
To increase the capacity of the hard drive
Explanation:
A semaphore is a synchronization primitive used to coordinate concurrent execution and control access to shared resources through operations that change or wait on its count.
Q.
Which scheduling algorithm can cause starvation when shorter jobs continually arrive?
A strictly fair cyclic scheduler
First-Come, First-Served
Round Robin with a fixed time quantum
Shortest Job First
Explanation:
Non-preemptive Shortest Job First scheduling may indefinitely delay a long job if shorter jobs repeatedly arrive and are selected ahead of it.
Q.
What is thrashing in a virtual memory system?
The permanent deletion of virtual memory
The conversion of physical memory into cache memory
Excessive paging that leaves little time for useful execution
The process of increasing the CPU's clock speed
Explanation:
Thrashing occurs when excessive page faults cause the system to spend most of its time transferring pages between RAM and secondary storage rather than executing useful work.
Q.
Which page replacement algorithm replaces the page that has not been used for the longest time in the past?
Round Robin
Least Recently Used
First-Come, First-Served
First-In, First-Out
Explanation:
Least Recently Used (LRU) replaces the page whose most recent access occurred furthest in the past. It uses past access history to approximate which page is least likely to be needed soon.
Q.
What is the purpose of a system call?
To replace the computer's BIOS permanently
To increase the number of CPU cores
To physically connect a monitor to the computer
To request operating system services from a user-space program
Explanation:
A system call provides a controlled interface through which a user-space program requests services from the operating system kernel, such as file access or process creation.
Q.
Which of the following is one of the four necessary conditions for deadlock?
Guaranteed resource preemption
Automatic process completion
Unlimited parallel execution
Circular wait
Explanation:
Circular wait occurs when processes form a cycle in which each process waits for a resource held by the next process. Together with mutual exclusion, hold and wait, and no preemption, it forms the four Coffman conditions for deadlock.
Q.
In a Unix-like operating system, what does the fork() system call typically do?
Creates a new process
Formats the entire hard drive
Deletes the operating system kernel
Changes the processor's physical architecture
Explanation:
The fork() system call creates a new process by duplicating the calling process. The child receives a separate process identity, and memory is commonly managed using copy-on-write.
Q.
What is a race condition?
A file being copied between two directories
A hardware component overheating during startup
A process running faster than the CPU clock
A program's result depending on the timing or ordering of concurrent operations
Explanation:
A race condition occurs when the result of a computation depends on the timing or ordering of concurrent operations accessing shared state, and the operations are not adequately coordinated.
Q.
What is the primary difference between preemptive and non-preemptive CPU scheduling?
There is no difference between the two approaches
Preemptive scheduling allows the operating system to interrupt a running process
Preemptive scheduling works only on computers without memory
In preemptive scheduling, the operating system can interrupt a running process and allocate the CPU to another process. In non-preemptive scheduling, a running process retains the CPU until it terminates or voluntarily yields or blocks.
Q.
What is the main purpose of a Translation Lookaside Buffer (TLB)?
To speed up virtual-to-physical address translation
To store copies of all user documents
To manage network routing tables exclusively
To schedule processes according to their priority
Explanation:
A TLB is a small, fast cache that stores recently used virtual-to-physical address translations. A TLB hit avoids the need to perform a full page-table lookup for that translation.
Q.
What is a process in the context of operating systems?
A device driver for a printer
A program in execution
A hardware component like the CPU
A static file stored on the hard drive
Explanation:
A process is a program in execution, representing an active unit of work.
Q.
Which data structure is typically used to represent a process's control information in the OS?
Queue
Stack pointer table
Process Control Block (PCB)
Inverted index
Explanation:
The Process Control Block (PCB) contains all the information needed about a specific process.
Q.
Which of the following scheduling algorithms is non-preemptive?
Shortest Remaining Time First
Round Robin
First-Come, First-Served (FCFS)
Priority Preemptive
Explanation:
First-Come, First-Served (FCFS) is strictly non-preemptive as once the CPU has been allocated to a process, it keeps the CPU until it releases it.
Q.
What is Belady's anomaly associated with?
CPU scheduling algorithms
Deadlock avoidance algorithms
Disk head scheduling algorithms
Page replacement algorithms like FIFO
Explanation:
Belady's anomaly describes the phenomenon where increasing the number of page frames results in an increase in the number of page faults for certain memory access patterns under FIFO.
Q.
What is a semaphore primarily used for?
Network packet routing
Process synchronization
Memory allocation
File system backup
Explanation:
A semaphore is a synchronization tool used to manage concurrent processes and solve critical section problems.
Q.
Which conditions must hold simultaneously for a deadlock to occur?
Mutual Exclusion, Hold and Wait, No Preemption, Circular Wait
Explanation:
Coffman conditions for deadlock are Mutual Exclusion, Hold and Wait, No Preemption, and Circular Wait.
Q.
What does Thrashing mean in an operating system?
The CPU is running at maximum frequency
Processes spend more time paging than executing instructions
Network connections are dropping packets continuously
The hard disk drive has experienced a mechanical failure
Explanation:
Thrashing occurs when a system spends more time paging (swapping pages in and out of memory) than executing actual instructions.
Q.
Which of the following system calls creates a new process in UNIX-like operating systems?
spawn()
exec()
fork()
clone()
Explanation:
The fork() system call creates a new child process that is a duplicate of the calling process.
Q.
What is the primary objective of a time-sharing operating system?
To eliminate the need for secondary storage
To maximize hardware cost efficiency
To minimize response time
To run batch jobs overnight without interaction
Explanation:
Time-sharing systems switch the CPU among processes so frequently that users can interact with each program while it is running, minimizing response time.
Q.
What is a thread?
A lightweight process within a process
A type of physical memory chip
An input-output hardware control bus
A heavyweight process with its own address space
Explanation:
A thread is a lightweight process, representing the basic unit of CPU utilization.
Q.
Which page replacement algorithm replaces the page that has not been used for the longest period of time?
Random Replacement
Optimal Page Replacement
Least Recently Used (LRU)
FIFO
Explanation:
Least Recently Used (LRU) uses past knowledge to replace the page that hasn't been referenced for the longest time.
Q.
What is the main function of the kernel?
To translate high-level code into bytecode
To handle user account passwords exclusively
To provide graphic web browsing capabilities
To manage system resources and act as the core of the OS
Explanation:
The kernel is the core component of the operating system that manages system resources and hardware communication.
Q.
Which memory management technique eliminates external fragmentation?
Variable partition allocation
Paging
Contiguous memory allocation
Segmentation
Explanation:
Paging divides physical memory into fixed-size blocks called frames and logical memory into blocks called pages, completely eliminating external fragmentation.
Q.
What is a page fault?
An interruption when a requested page is not in physical memory
A security violation caused by unauthorized access
A hardware failure in the RAM stick
A syntax error detected by the compiler
Explanation:
A page fault occurs when a program attempts to access a memory page that is not currently mapped in physical RAM.
Q.
What is the Banker's algorithm used for?
Memory compression
Deadlock avoidance
Disk defragmentation
Process scheduling
Explanation:
The Banker's algorithm is a resource allocation and deadlock avoidance algorithm that tests for safety conditions.
Q.
Which component provides the interface between user applications and the operating system services?
Loaders
Linkers
System calls
Compilers
Explanation:
System calls provide the interface between a running program and the operating system.
Q.
Which disk scheduling algorithm moves the disk arm to the end of the disk servicing requests in one direction before reversing?
SCAN
FCFS
SSTF
C-LOOK
Explanation:
The SCAN disk scheduling algorithm (elevator algorithm) moves continuously toward one end, servicing requests until it reaches the end, then reverses direction.
Q.
What is context switching?
Switching a computer from sleep mode to active mode
Saving the state of a current process and loading the state of another
Moving data between primary memory and secondary storage
Changing the user interface theme
Explanation:
Context switching involves storing the context or state of a current process so that it can be restored later, and loading the state of another process.
Q.
What is virtual memory?
An illusion of a large memory maintained by using disk space as an extension of RAM
Read-only memory storing the bootloader
Cache memory integrated directly inside the CPU die
A cloud storage system managed by the browser
Explanation:
Virtual memory is a memory management capability that uses hardware and software to allow a computer to compensate for physical memory shortages by temporarily transferring data from RAM to disk storage.
Q.
Which file allocation method uses a linked list of disk blocks for each file?
Contiguous allocation
Direct allocation
Linked allocation
Indexed allocation
Explanation:
Linked allocation links each file as a linked list of disk blocks, where each block contains a pointer to the next block.
Q.
Which of the following is an example of a batch operating system?
Android 14
Windows 10
macOS Sonoma
IBM OS/360
Explanation:
Batch systems execute jobs with similar needs in batches without user interaction during execution, common in early mainframe systems.
Q.
What does RAID stand for in storage management?
Redundant Array of Independent Disks
Remote Application Interface Data
Random Access Information Directory
Rapid Access Internal Device
Explanation:
RAID stands for Redundant Array of Independent Disks, used to improve performance and reliability.
Q.
What is spooling?
Placing data in temporary storage for a peripheral device to access later
Compressing large files to save disk space
Spreading process threads across multiple CPU sockets
Encrypting network streams against interception
Explanation:
SPOOLing (Simultaneous Peripheral Operations On-Line) is a process where data is held in temporary storage to be used by a device later, commonly used for printing.
Q.
Which scheduling metric measures the total time spent from submission of a process to its completion?
Response time
Waiting time
Throughput
Turnaround time
Explanation:
Turnaround time is the total time taken to execute a process from its arrival time to its completion time.
Q.
What is a microkernel architecture?
An architecture that structures the OS by removing non-essential components from the kernel
A kernel that fits entirely within the L1 CPU cache
An architecture where all OS services run inside kernel space
An operating system designed exclusively for microcontrollers
Explanation:
A microkernel structures the operating system by removing all non-essential components from the kernel and implementing them as system programs in user space.
Q.
What is the purpose of the program counter (PC) register in a process state?
To hold the address of the next instruction to be executed
To record the total CPU ticks consumed
To store the total memory size allocated to the process
To count the number of system calls made
Explanation:
The program counter holds the address of the next instruction to be executed for that process.
Q.
Which of the following is NOT a valid process state?
Compile
Ready
Terminated
Running
Explanation:
Standard process states include New, Ready, Running, Waiting (Blocked), and Terminated. 'Compile' is not a process state.
Q.
What is internal fragmentation?
Data corruption inside the CPU cache registers
Free memory scattered in small blocks between allocated partitions
Unused space left inside an allocated memory block
Disorganized files on a fragmented hard disk drive
Explanation:
Internal fragmentation occurs when allocated memory blocks are larger than the requested memory, leaving unused space inside the partition.
Q.
What is external fragmentation?
Hard drive sectors damaged by magnetic wear
Unused memory space within a single allocated partition
Network data packets lost during transmission
Sufficient total free memory exists, but it is not contiguous
Explanation:
External fragmentation happens when total free memory is enough to satisfy a request, but it is not contiguous.
Q.
Which scheduling algorithm can suffer from the convoy effect?
Multilevel Feedback Queue
Shortest Job First
Round Robin
First-Come, First-Served (FCFS)
Explanation:
The convoy effect occurs in FCFS when shorter processes wait behind a long CPU-bound process.
Q.
What is aging in operating systems scheduling?
Removing old files from the system automatically
Recycling physical RAM sticks after years of usage
Reducing CPU frequency to save battery life over time
Gradually increasing the priority of processes that wait for a long time to prevent starvation
Explanation:
Aging is a technique of gradually increasing the priority of processes that wait in the system for a long time to prevent starvation.
Q.
What is the primary function of a device driver?
To act as a graphical user interface for applications
To translate operating system commands into hardware-specific operations for a device
To supply electrical power to hardware components
To connect the computer to wireless internet access points
Explanation:
A device driver is a specific program that controls or operates a particular device attached to a computer, providing an interface to the OS.
Q.
Which of the following is a synchronization mechanism that can be implemented in hardware?
Message passing queues
Inode structures
Test-and-Set instruction
Paging tables
Explanation:
Test-and-Set and Compare-and-Swap are atomic hardware instructions used to implement mutual exclusion and semaphores.
Q.
What is a monolithic kernel?
A cloud-based kernel running on distributed virtual servers
A minimal kernel containing only process scheduling and memory management
A kernel where all operating system services run in kernel space as a single large program
An embedded kernel stored entirely in read-only ROM
Explanation:
A monolithic kernel is an operating system architecture where the entire operating system works in kernel space and runs in a single address space.
Q.
What is a real-time operating system (RTOS)?
An OS that tracks physical time zone changes globally
An OS used exclusively for high-end graphic rendering and gaming
An OS that guarantees processing data within strict, fixed time constraints
An OS with no concept of multitasking or scheduling
Explanation:
An RTOS is an operating system intended to serve real-time applications that process data as it comes in with strict timing constraints.
Q.
What is the function of the Translation Lookaside Buffer (TLB)?
To keep track of open files and directory pointers
To store recently used virtual-to-physical address translations for fast lookup
To store user login credentials securely
To buffer network packets before sending them over Ethernet
Explanation:
The TLB is a special fast-lookup hardware cache used to speed up virtual-to-physical address translation.
Q.
Which storage placement strategy allocates the smallest hole that is big enough to satisfy a memory request?
Next-fit
First-fit
Worst-fit
Best-fit
Explanation:
Best-fit allocates the smallest hole from the list of available free holes that is large enough.
Q.
What is dynamic loading?
Allocating virtual memory pages dynamically on demand
Loading routines into memory only when they are actually called
Swapping entire memory partitions to disk during runtime
Updating device driver software automatically over the internet
Explanation:
Dynamic loading is a routine loaded into memory only when it is called, improving memory space utilization.
Q.
What is dynamic linking?
Binding memory addresses during compile time
Connecting network sockets dynamically between clients
Merging multiple source code files into a single object file
Linking system libraries to the executable only at execution time
Explanation:
Dynamic linking postpones the linking of library routines until execution time, reducing executable file size.
Q.
Which of the following describes mutual exclusion?
Only one process can execute in its critical section at a time
Two processes can never execute on separate CPU cores
Processes must share CPU time equally without priority
All processes can access shared resources simultaneously
Explanation:
Mutual exclusion ensures that if one process is executing in its critical section, no other processes can execute in their critical sections.
Q.
What is a bootstrap program?
An application used to format hard drives during installation
A network tool used to test connection speeds
A program stored in ROM that initializes hardware and loads the OS kernel
A user-mode utility that manages desktop themes
Explanation:
The bootstrap program is stored in ROM or EPROM and initializes hardware, loads the kernel, and starts the OS.
Q.
What is an interrupt?
A command that shuts down the operating system safely
A signal to the processor indicating an event that requires immediate attention
An error that permanently damages the CPU arithmetic unit
A pause in user keyboard input due to inactivity
Explanation:
An interrupt is a signal to the processor emitted by hardware or software indicating an event that needs immediate attention.
Q.
What is direct memory access (DMA)?
The physical wiring connecting the CPU to the RAM slots
A method for programs to bypass security checks and access RAM directly
A feature allowing devices to transfer data directly to/from memory without CPU intervention
A technique for expanding virtual memory using flash drives
Explanation:
DMA allows hardware subsystems to access main system memory independently of the central processing unit.
Q.
Which scheduler selects processes from the ready queue and allocates the CPU to one of them?
Long-term scheduler (job scheduler)
I/O scheduler
Medium-term scheduler (swapper)
Short-term scheduler (CPU scheduler)
Explanation:
The short-term scheduler (or CPU scheduler) selects which process should be executed next and allocates CPU time.
Q.
What is the primary role of the long-term scheduler?
To allocate CPU time slices every few milliseconds
To manage virtual memory page swaps to disk
To control peripheral device drivers during startup
To select processes from job storage and load them into memory
Explanation:
The long-term scheduler (job scheduler) selects processes from a pool and loads them into memory for execution.
Q.
What does a medium-term scheduler do?
Decides which thread runs on which CPU core
Swaps processes between main memory and secondary storage
Schedules disk track head movements
Manages network socket connections over time
Explanation:
The medium-term scheduler removes processes from memory (swapping) to reduce the degree of multiprogramming and later re-introduces them.
Q.
What is a zombie process?
A malicious malware process hidden inside system files
A process that refuses to terminate when killed by the user
A process stuck in an infinite loop consuming 100% CPU
A process that has finished execution but still has an entry in the process table
Explanation:
A zombie process is a process that has completed execution but still has an entry in the process table, usually because its parent has not yet read its exit status.
Q.
What is an orphan process?
A child process whose parent process has terminated
A file that is no longer linked to any directory
A process running without any memory allocation
A thread whose parent process crashed unexpectedly
Explanation:
An orphan process is a child process whose parent process has finished or terminated, leaving it to be adopted by the init process.
Q.
Which of the following is an example of inter-process communication (IPC)?
Compilation and linking
Caching and buffering
Shared memory and message passing
Paging and segmentation
Explanation:
Shared memory and message passing are standard mechanisms for inter-process communication.
Q.
What is a critical section?
A section of the kernel responsible for handling hardware errors
A code segment that accesses shared resources prone to race conditions
Encrypted memory reserved for security credentials
The boot sequence code executed when the PC starts
Explanation:
A critical section is a piece of code that accesses shared variables or resources that can lead to race conditions if executed concurrently.
Q.
What is a monitor in concurrency?
A logging daemon that records system error messages
A hardware display screen controller driver
A diagnostic tool for monitoring CPU temperature and voltage
A synchronization construct providing mutual exclusion and conditional waiting
Explanation:
A monitor is a synchronization construct that allows threads to have both mutual exclusion and the ability to wait for certain conditions.
Q.
What is spinlock?
A mechanism that locks hard drive platters during sudden physical movement
A lock where a thread waits in a loop repeatedly checking if it becomes available
A process scheduling queue that cycles in a round-robin order
A security feature that locks user accounts after failed login attempts
Explanation:
A spinlock is a lock where a thread trying to acquire it simply waits in a loop ("spin") while repeatedly checking if the lock is available.
Q.
What is priority inversion?
When a high-priority process is indirectly blocked by a low-priority process holding a resource
When background tasks run faster than foreground applications
When a user manually lowers the priority of system services
When the operating system reverses process priorities randomly
Explanation:
Priority inversion occurs when a high-priority process is indirectly preempted by a lower-priority process holding a required resource.
Q.
Which page replacement algorithm replaces the page that will not be used for the longest time in the future?
First-In, First-Out (FIFO)
Clock page replacement
Optimal page replacement algorithm
Least Recently Used (LRU)
Explanation:
The Optimal page replacement algorithm looks forward in time and replaces the page that won't be needed for the longest time.
Q.
What is the primary purpose of hierarchical paging?
To break down large page tables so they do not need to be contiguous in memory
To prioritize high-priority tasks over background processes
To encrypt virtual memory pages against unauthorized access
To speed up disk read and write speeds for large files
Explanation:
Hierarchical paging breaks the page table into smaller pieces to avoid keeping an entire large page table contiguous in memory.
Q.
What is an inverted page table?
A page table structure with one entry per physical frame instead of per virtual address
A backup table used when the primary page table becomes corrupted
A table that stores physical addresses in reverse numerical order
A directory structure used exclusively for inverted file systems
Explanation:
An inverted page table has one entry for each real page frame of memory, saving significant memory space.
Q.
What is segmentation in memory management?
Splitting hard drive storage into equal sectors and tracks
Dividing memory into logical variable-sized segments like code, data, and stack
Separating network traffic into individual TCP packets
Dividing CPU time slices among active user threads
Explanation:
Segmentation is a memory management scheme that divides memory into logical variable-sized segments like code, data, and stack.
Q.
What is the main advantage of user-level threads over kernel-level threads?
Thread management and switching can be done fast without kernel intervention
The kernel automatically handles all scheduling without library overhead
They have direct access to physical hardware registers
They can run on multiple CPU cores simultaneously without OS support
Explanation:
User-level threads are managed by user-space libraries, allowing fast creation and switching without kernel intervention.
Q.
What is a file descriptor?
A text metadata string describing the creation date of a file
An integer handle used by a process to identify and access an open file
The physical sector address where file data begins on disk
An encryption key used to protect private user documents
Explanation:
A file descriptor is an abstract integer handle used by a process to identify and access an open file.
Q.
What is an inode in UNIX file systems?
An input node used for managing keyboard and mouse interrupts
A network socket identifier used for remote file mounting
A data structure storing file metadata and block pointers, excluding filename and content
The root directory folder that contains all other system files
Explanation:
An inode is a data structure that stores metadata about a file, excluding its filename and content.
Q.
What is a hard link in a file system?
A directory entry that points directly to the same underlying inode as another filename
A read-only backup copy stored on secondary storage
A shortcut pointer file that redirects to a different directory path
A physical connection cable linking two separate hard drives
Explanation:
A hard link points directly to the inode of a file, allowing multiple directory entries to reference the same inode.
Q.
What is a symbolic link (soft link)?
A virtual file created dynamically by the kernel in RAM
A direct pointer to an inode sharing the exact same file blocks
A compressed archive containing multiple backup files
A file containing a path reference to another file or directory
Explanation:
A symbolic link contains a reference path to another file or directory.
Q.
Which disk scheduling algorithm selects the request closest to the current head position?
C-SCAN
FIFO
First-Come, First-Served (FCFS)
Shortest Seek Time First (SSTF)
Explanation:
Shortest Seek Time First (SSTF) selects the disk request that requires the minimum head movement from the current position.
Q.
What is C-SCAN (Circular SCAN) disk scheduling?
A random disk access algorithm designed for solid-state drives
A variation of SCAN that services requests in only one direction, returning immediately to the beginning
An algorithm that prioritizes inner tracks over outer tracks exclusively
A scheduling method that reverses direction every time a single request is completed
Explanation:
C-SCAN services requests in one direction and immediately returns to the beginning without servicing requests on the return trip.
Q.
What is write-through caching in file systems?
Data is written directly to secondary tape backups
Data is written only to cache and delayed until disk flush
Data is written into the cache and immediately written to disk as well
Data bypasses cache entirely and goes straight to disk sectors
Explanation:
Write-through updates data in cache and simultaneously writes it to disk storage to maintain data integrity.
Q.
What is write-back (write-deferred) caching?
Modifications are written to disk immediately and cached afterwards
Data is mirrored across two physical disks simultaneously
Writing is disabled until the system encounters a low memory warning
Modifications are written to cache first and delayed until cache blocks are replaced
Explanation:
Write-back caching writes modifications to cache first, delaying disk writes until cache blocks are replaced.
Q.
What is an access control matrix in operating system security?
A matrix used for calculating virtual-to-physical memory addresses
A scheduling queue priority assignment table
A table defining permissions of subjects over objects in the system
A network firewall routing rule table
Explanation:
An access control matrix defines permissions of subjects over objects in the system.
Q.
What is a capability list in file and resource protection?
A list associated with a domain specifying authorized objects and permissions
A registry of installed device drivers
A list of hardware instructions supported by the CPU architecture
A list of running processes eligible for CPU scheduling
Explanation:
A capability list is associated with a domain specifying authorized objects and permissions.
Q.
What is a hypervisor?
Software or firmware that creates and runs virtual machines
A high-speed network router connecting data center servers
An advanced file system manager for RAID arrays
A tool that monitors CPU clock speeds and temperatures
Explanation:
A hypervisor is software, firmware, or hardware that creates and runs virtual machines.
Q.
What is the main difference between Type 1 and Type 2 hypervisors?
Type 1 handles memory virtualization, while Type 2 handles I/O virtualization
Type 1 supports Windows only, while Type 2 supports Linux only
Type 1 is software-based, while Type 2 is strictly hardware-based
Type 1 runs on bare metal hardware, while Type 2 runs on a host operating system
Explanation:
Type 1 hypervisors run directly on bare metal hardware, while Type 2 run on top of an existing host OS.
Q.
What is symmetric multiprocessing (SMP)?
A network of independent computers sharing workload over Ethernet
A system where one master processor controls all slave processors
A single processor executing multiple threads using hyper-threading
An architecture where multiple identical processors share main memory and run the OS concurrently
Explanation:
In SMP, multiple processors share main memory and run the OS concurrently with equal access.
Q.
What is asymmetric multiprocessing?
An architecture where a master processor assigns tasks to slave processors
Running different operating systems on separate partitions
An architecture where all processors have equal access to all resources
A technique where CPU cores dynamically adjust voltage based on workload
Explanation:
In asymmetric multiprocessing, a master processor manages and assigns tasks to slave processors.
Q.
What is a bootstrap loader?
A small program that locates and loads the main OS kernel into memory
A tool that boots up connected USB peripheral devices
A network utility that downloads system updates
An application loader that starts user desktop programs
Explanation:
The bootstrap loader is a small program responsible for locating and loading the OS kernel into memory.
Q.
What is the purpose of the ready queue?
To hold processes that are ready and waiting for CPU execution time
To buffer files before they are written to disk
To keep track of terminated processes before cleanup
To store processes currently waiting for I/O completion
Explanation:
The ready queue holds all processes that are ready and waiting to execute on the CPU.
Q.
What is a device queue?
A queue of print jobs waiting in the spooler
A list of hardware devices installed in the device manager
A queue of processes waiting for a specific I/O device
A buffer for storing network packets before routing
Explanation:
A device queue holds processes waiting for a specific I/O device.
Q.
What is multiprogramming?
Holding multiple programs in main memory to increase CPU utilization
Compiling source files using parallel compiler threads
Running multiple operating systems inside virtual machines
Writing code in multiple programming languages simultaneously
Explanation:
Multiprogramming keeps multiple programs in main memory so the CPU always has something to execute.
Q.
What is the degree of multiprogramming?
The total capacity of installed RAM in gigabytes
The number of processes residing in main memory at one time
The number of user accounts configured on the machine
The number of CPU cores active in the system
Explanation:
The degree of multiprogramming refers to the number of processes in main memory at a given time.
Q.
What is CPU utilization?
The speed at which the CPU clock ticks per second
The ratio of cache memory hits to misses
The percentage of time the processor is busy executing instructions
The amount of electric power consumed by the CPU core
Explanation:
CPU utilization measures the percentage of time the CPU is actively executing instructions.
Q.
What is throughput in CPU scheduling?
The response time of interactive user commands
The data transfer rate of the hard disk controller
The total amount of memory allocated to all running jobs
The number of processes completed per time unit
Explanation:
Throughput is the number of processes completed per unit of time.
Q.
What is waiting time in CPU scheduling?
The duration of an I/O request operation
The time taken to load a program from disk into RAM
The total time a process spends waiting in the ready queue
The time elapsed between user login and desktop load
Explanation:
Waiting time is the total amount of time a process spends waiting in the ready queue.
Q.
What is response time in interactive systems?
The delay before a hardware interrupt is acknowledged
The total time required to complete an entire job
The time taken for a context switch to finish
The time from submission of a request until the first response is produced
Explanation:
Response time is the time from request submission until the first response is produced.
Q.
Which scheduling algorithm assigns execution time slices to each process in a cyclic order?
First-Come, First-Served
Shortest Job First
Round Robin
Priority Scheduling
Explanation:
Round Robin (RR) assigns a fixed time quantum to each process in cyclic order.
Q.
What happens in Round Robin scheduling if the time quantum is extremely large?
All processes suffer from immediate starvation
It becomes equivalent to Shortest Job First scheduling
The system experiences excessive context switching overhead
It degenerates into First-Come, First-Served (FCFS) scheduling
Explanation:
If the time quantum is very large, Round Robin degenerates into First-Come, First-Served (FCFS) scheduling.
Q.
What happens in Round Robin scheduling if the time quantum is extremely small?
It converts into a non-preemptive FCFS scheduling queue
It causes high overhead due to excessive context switching
CPU utilization drops to zero permanently
Processes complete execution instantly without delay
Explanation:
If the time quantum is too small, frequent context switches create significant overhead.
Q.
What is multilevel queue scheduling?
Executing multiple kernel threads simultaneously across CPU cores
Using a single queue that sorts processes by strict numerical priority
Partitioning the ready queue into multiple separate queues with individual scheduling algorithms
Moving processes dynamically between RAM and disk storage partitions
Explanation:
Multilevel queue scheduling partitions the ready queue into separate queues with distinct algorithms.
Q.
What is multilevel feedback queue scheduling?
A fixed queue system where processes can never change their assigned queue
A memory allocation policy using feedback loops to prevent fragmentation
A disk I/O scheduling algorithm that optimizes read head positions
A scheduler allowing processes to move between queues based on execution behavior and waiting time
Explanation:
Multilevel feedback queue scheduling allows processes to move between queues based on execution behavior and aging.
Q.
What is a resource allocation graph used for?
To schedule disk track head movements efficiently
To map virtual memory addresses to physical RAM frames
To organize directory hierarchies in a file system
To model process resource requests and allocations for deadlock detection
Explanation:
A resource allocation graph models process resource requests and allocations to detect or avoid deadlocks.
Q.
What is a safe state in deadlock avoidance?
A state where no processes are currently running in memory
A state where the system can allocate resources to all processes in some order without deadlocking
A system state where all files are backed up to cloud storage
A security mode preventing unauthorized user login attempts
Explanation:
A state is safe if the OS can allocate resources to all processes in some order without encountering a deadlock.
Q.
What is a safe sequence?
A priority ranking of threads in the short-term ready queue
An execution order of processes such that each can acquire its required resources safely
An ordered list of disk blocks forming a contiguous file
A sequence of boot instructions stored in the motherboard BIOS
Explanation:
A safe sequence is an execution order of processes such that each process can safely acquire its needed resources.
Q.
What is starvation (indefinite blocking)?
A condition where physical memory runs completely out of free space
A situation where a process is perpetually denied necessary resources to execute
An error where the CPU overheats due to lack of cooling fan power
A network timeout caused by weak Wi-Fi signal strength
Explanation:
Starvation is a scenario where a process is perpetually denied required resources to execute.
Q.
What is logical address space?
The cache memory addresses inside the processor core
The physical locations of RAM chips installed on the motherboard
The total storage capacity of the hard disk drive partition
The set of all logical addresses generated by the CPU for a program
Explanation:
Logical address space is the set of all logical addresses generated by the CPU for a program.
Q.
What is physical address space?
The register addresses used by assembly language instructions
The virtual memory swap space allocated on secondary disk storage
The network IP address assigned to the computer interface
The set of all physical addresses corresponding to memory unit locations
Explanation:
Physical address space is the set of all physical addresses corresponding to memory unit locations.
Q.
What is the memory management unit (MMU)?
An operating system daemon handling process swapping
A software utility that cleans up unused RAM files
A hardware component that transforms virtual addresses into physical addresses
A storage controller managing SSD flash translation layers
Explanation:
The MMU is a hardware device that transforms virtual addresses into physical addresses.
Q.
What is a relocation register?
A register tracking the number of page faults encountered
A pointer to the top of the process call stack
A hardware register storing the current program execution counter
A register containing the base physical address added to logical addresses for relocation
Explanation:
The relocation register contains the base physical address added to every logical address for relocation.
Q.
What is swapping in memory management?
Switching the active desktop user profile
Exchanging two active threads on the same CPU core
Replacing a failing RAM stick with a new hardware module
Temporarily moving a process between main memory and secondary storage disk
Explanation:
Swapping involves temporarily moving a process between main memory and secondary storage disk.
Q.
What is a page table?
A directory listing all user accounts and permissions
A queue schedule table for short-term CPU tasks
A table tracking available hard disk blocks and file sectors
A data structure used to map virtual addresses to physical memory frames
Explanation:
A page table is a data structure mapping virtual addresses to physical memory frames.
Q.
What is demand paging?
Loading the entire program into RAM before execution begins
Loading pages into memory only when they are referenced during execution
Streaming video data over a network connection
Allocating fixed disk partitions upon user request
Explanation:
Demand paging loads pages into memory only when they are referenced during execution.
Q.
What is the second-chance (clock) page replacement algorithm?
A disk scheduling method synchronized with hardware timer chips
A CPU scheduling algorithm based on wall-clock time intervals
A page replacement algorithm using a reference bit and a circular pointer resembling a clock hand
An algorithm that replaces pages twice a second to keep memory clean
Explanation:
The clock algorithm uses a reference bit and a circular queue pointer to give pages a second chance.
Q.
What is the working set model in virtual memory?
A model based on program locality defining the set of pages currently in active use
A configuration setting for network file sharing permissions
A hardware specification defining minimum RAM requirements
A software suite used by developers to write operating system code
Explanation:
The working set model defines the set of pages currently in active use based on locality of reference.