101. What characterizes a hard real-time system?
- a) Deadline misses cause system failure
- b) Supports best-effort timing
- c) Uses probabilistic deadlines
- d) Tolerates occasional delays
Answer: A - Hard RTOS (e.g., airbag control) requires guaranteed response times.
102. Which security mechanism prevents buffer overflow attacks?
- a) Address Space Layout Randomization (ASLR)
- b) Round Robin Scheduling
- c) Demand Paging
- d) Disk Defragmentation
Answer: A - ASLR randomizes memory addresses to thwart exploit predictability.
103. What is priority inheritance protocol used for?
- a) Prevents priority inversion in real-time systems
- b) Increases cache hit ratio
- c) Optimizes disk seek times
- d) Manages virtual memory allocation
Answer: A - Temporarily boosts low-priority tasks holding needed resources.
104. Which Linux security module enforces mandatory access control?
- a) SELinux
- b) iptables
- c) sudo
- d) chmod
Answer: A - SELinux uses security contexts for fine-grained process/resource control.
105. What is the main purpose of RCU (Read-Copy-Update) synchronization?
- a) Lock-free reads for scalable performance
- b) Encrypt memory pages
- c) Schedule I/O operations
- d) Defragment swap space
Answer: A - Used in Linux kernel for concurrent read-heavy data structures.
106. Which Windows feature provides application sandboxing?
- a) AppContainer
- b) Registry Editor
- c) Task Scheduler
- d) Device Manager
Answer: A - Isolates Universal Windows Apps with restricted capabilities.
107. What is "tickless kernel" in modern OS?
- a) Reduces power usage by eliminating periodic interrupts
- b) Kernel without timing support
- c) Filesystem without timestamps
- d) CPU without clock cycle counting
Answer: A - Allows processors to enter deeper sleep states (Linux/Windows).
108. Which algorithm solves the readers-writers problem with writer priority?
- a) Second Readers-Writers Solution
- b) Peterson's Algorithm
- c) Banker's Algorithm
- d) Round-Robin Scheduling
Answer: A - Uses two semaphores to prevent writer starvation.
109. What does TPM (Trusted Platform Module) provide?
- a) Hardware-based cryptographic security
- b) Thermal protection for CPU
- c) Memory compression
- d) Disk encryption
Answer: A - Stores encryption keys and enables secure boot.
110. Which scheduling policy is best for multimedia systems?
- a) Earliest Deadline First (EDF)
- b) Shortest Job First
- c) Multilevel Feedback Queue
- d) First-Come-First-Serve
Answer: A - EDF dynamically prioritizes tasks closest to deadlines.
111. What is "TOCTTOU" vulnerability in OS security?
- a) Time-of-Check to Time-of-Use race condition
- b) Memory corruption attack
- c) Disk sector corruption
- d) Network packet sniffing
Answer: A - Occurs when system state changes between validation and use.
112. Which Linux kernel subsystem manages real-time tasks?
- a) SCHED_FIFO/SCHED_RR
- b) CFS (Completely Fair Scheduler)
- c) O(1) Scheduler
- d) Deadline Scheduler
Answer: A - Provides fixed-priority preemptive scheduling (RT patches).
113. What is "memory ballooning" in virtualization?
- a) Dynamically reallocates RAM between VMs
- b) Compresses memory pages
- c) Defragments virtual memory
- d) Encrypts guest OS memory
Answer: A - Hypervisor "inflates" balloon driver to reclaim memory.
114. Which Windows component enforces code integrity?
- a) Kernel Patch Protection (PatchGuard)
- b) Windows Defender
- c) Task Manager
- d) Registry Editor
Answer: A - Prevents unauthorized kernel modifications (64-bit systems).
115. What is "RCU (Read-Copy-Update)" in Linux kernel?
- a) Lock-free synchronization for read-mostly data
- b) RAID configuration utility
- c) Remote CPU utilization
- d) Registry cleanup tool
Answer: A - Enables concurrent reads/writes without blocking.
116. Which filesystem feature prevents data corruption during crashes?
- a) Journaling (e.g., ext3, NTFS)
- b) Disk defragmentation
- c) File compression
- d) Block allocation
Answer: A - Logs changes before committing to disk structures.
117. What is "cache coloring" in memory management?
- a) Reduces cache conflicts by strategic page allocation
- b) GPU-accelerated rendering
- c) Memory compression technique
- d) Disk caching algorithm
Answer: A - Important for real-time systems with strict latency requirements.
118. Which mechanism prevents Spectre/Meltdown CPU vulnerabilities?
- a) Kernel page-table isolation (KPTI)
- b) Address Space Layout Randomization
- c) Stack canaries
- d) Memory ballooning
Answer: A - Separates user/kernel address spaces (performance overhead).
119. What is "deterministic scheduling" in RTOS?
- a) Guaranteed worst-case response times
- b) Probabilistic task completion
- c) Randomized priority assignment
- d) Best-effort execution
Answer: A - Critical for industrial control and avionics systems.
120. Which Windows API provides container isolation?
- a) Job Objects API
- b) Win32 API
- c) DirectX API
- d) WMI API
Answer: A - Limits resource usage for process groups (used by Docker).