Memory Protection and Privilege Levels MCQs

What is the primary purpose of memory protection in an operating system?
A) To prevent unauthorized access to hardware
B) To prevent processes from accessing each other’s memory
C) To allow processes to execute at higher privilege levels
D) To ensure optimal memory allocation
Answer: B) To prevent processes from accessing each other’s memory

Which hardware component is responsible for enforcing memory protection?
A) CPU
B) Memory Management Unit (MMU)
C) Cache
D) Disk Controller
Answer: B) Memory Management Unit (MMU)

What is the purpose of privilege levels in a computer system?
A) To allow access to different parts of memory
B) To restrict access to certain system resources and instructions
C) To improve the speed of system calls
D) To prioritize process execution
Answer: B) To restrict access to certain system resources and instructions

What happens when a process tries to access a memory area it does not have permission to access?
A) It generates a segmentation fault
B) The operating system swaps the process out
C) It elevates its privilege level
D) The memory is allocated dynamically
Answer: A) It generates a segmentation fault

Which of the following describes kernel mode in terms of privilege levels?
A) The lowest privilege level where only user-level applications run
B) A high-privilege level that allows unrestricted access to system resources
C) A privilege level reserved for I/O devices
D) A mode that limits memory access to prevent corruption
Answer: B) A high-privilege level that allows unrestricted access to system resources

What is a memory protection violation also known as?
A) Page fault
B) Segmentation fault
C) Access violation
D) Cache miss
Answer: B) Segmentation fault

What is the role of a memory descriptor in memory protection?
A) To define the boundaries and access rights of a process’s memory
B) To allocate memory blocks contiguously
C) To store process instructions
D) To manage memory swapping between processes
Answer: A) To define the boundaries and access rights of a process’s memory

How does the MMU enforce memory protection?
A) By translating virtual addresses into physical addresses
B) By limiting access to memory based on privilege levels
C) By performing memory compaction
D) By managing cache memory
Answer: B) By limiting access to memory based on privilege levels

Which of the following describes user mode in a privilege-level system?
A) A mode with unrestricted access to memory
B) A low-privilege mode that restricts access to critical resources
C) A mode reserved for kernel processes
D) A privilege level that handles interrupt processing
Answer: B) A low-privilege mode that restricts access to critical resources

What is the purpose of the “no-execute” (NX) bit in memory protection?
A) To allow reading but prevent writing to memory
B) To prevent execution of code from certain memory regions
C) To allow a process to execute system calls
D) To allow access to privileged instructions
Answer: B) To prevent execution of code from certain memory regions

In a system with multiple privilege levels, which privilege level has the least access to memory and hardware resources?
A) Kernel mode
B) User mode
C) Supervisor mode
D) Hypervisor mode
Answer: B) User mode

What is the result of a process attempting to execute a privileged instruction while in user mode?
A) The instruction is executed successfully
B) The process is elevated to a higher privilege level
C) A trap or exception is generated
D) The instruction is ignored by the CPU
Answer: C) A trap or exception is generated

Which of the following is a primary feature of privilege separation in modern operating systems?
A) It allows user applications to run with unrestricted access
B) It isolates processes to prevent one from interfering with others
C) It reduces CPU load by combining user and kernel operations
D) It allows hardware components to run at the same privilege level as the OS
Answer: B) It isolates processes to prevent one from interfering with others

How does the operating system handle memory access violations?
A) By terminating the offending process
B) By allocating more memory to the process
C) By elevating the process’s privilege level
D) By transferring the process to kernel mode
Answer: A) By terminating the offending process

What is the purpose of page-level protection in memory management?
A) To allocate larger memory blocks
B) To control read, write, and execute permissions for each page
C) To manage the TLB for faster access
D) To reduce internal fragmentation
Answer: B) To control read, write, and execute permissions for each page

In a system with multiple privilege levels, what is the highest privilege level typically called?
A) User mode
B) Supervisor mode
C) Kernel mode
D) Ring 3
Answer: C) Kernel mode

What is a privilege escalation attack in the context of memory and privilege levels?
A) An attack that increases the memory allocated to a process
B) An attack where a user gains unauthorized higher-level access to the system
C) An attack that reduces the system’s memory protection
D) An attack that switches a process to user mode
Answer: B) An attack where a user gains unauthorized higher-level access to the system

Which memory protection mechanism is used to prevent a program from modifying its own code?
A) Read-only memory segments
B) Dynamic memory allocation
C) Stack protection
D) Data Execution Prevention (DEP)
Answer: D) Data Execution Prevention (DEP)

What does the term “ring protection” refer to in the context of privilege levels?
A) Layers of security that separate memory regions
B) The hardware mechanism to separate different levels of privilege
C) The method of locking memory to prevent access
D) The use of a cache to store memory protection data
Answer: B) The hardware mechanism to separate different levels of privilege

Which of the following is a consequence of a segmentation fault?
A) The operating system elevates the process’s privilege level
B) The process is terminated or a signal is sent to handle the fault
C) The CPU is forced to reset
D) The faulting process gains direct access to kernel memory
Answer: B) The process is terminated or a signal is sent to handle the fault

What is the function of supervisor mode in a system with multiple privilege levels?
A) To allow direct access to hardware resources
B) To manage process scheduling
C) To handle interrupts and system calls
D) To execute user-level applications
Answer: C) To handle interrupts and system calls

Which mechanism is used to enforce access control to different memory regions?
A) Memory-mapped I/O
B) Access Control Lists (ACLs)
C) Memory segmentation
D) Virtual memory
Answer: C) Memory segmentation

What is the result of a process running in user mode trying to access kernel mode memory?
A) The process is granted access
B) The operating system performs memory compaction
C) The system generates a memory access violation
D) The process switches to kernel mode
Answer: C) The system generates a memory access violation

How does the operating system restrict access to privileged CPU instructions?
A) By assigning them to supervisor processes only
B) By using privilege levels to allow only certain modes to execute them
C) By loading instructions dynamically into memory
D) By keeping privileged instructions in a separate memory segment
Answer: B) By using privilege levels to allow only certain modes to execute them

Which of the following mechanisms is used to isolate different user processes from each other in memory?
A) Paging
B) Memory segmentation
C) Cache memory
D) Address space separation
Answer: D) Address space separation

What does a “trap” refer to in the context of privilege levels and memory access?
A) A method of locking memory segments
B) A hardware interrupt triggered by a privileged instruction or memory violation
C) A process for performing memory compaction
D) A software mechanism to handle cache misses
Answer: B) A hardware interrupt triggered by a privileged instruction or memory violation

What is the consequence of a page-level memory protection violation?
A) The memory is reallocated
B) A page fault is generated
C) The process gains more privileges
D) The page is moved to the cache
Answer: B) A page fault is generated

What role does privilege separation play in system security?
A) It provides a direct connection between user applications and the kernel
B) It limits the scope of what user-level processes can do
C) It reduces the amount of memory used by processes
D) It ensures processes are scheduled more efficiently
Answer: B) It limits the scope of what user-level processes can do

What is an example of an action that can only be performed in kernel mode?
A) Modifying a system configuration file
B) Accessing hardware directly, such as disk or memory controllers
C) Creating a new user-level process
D) Executing a basic arithmetic operation
Answer: B) Accessing hardware directly, such as disk or memory controllers

What is the function of the CPU’s privilege level indicator?
A) It switches the CPU between different modes for executing instructions
B) It performs memory allocation based on process requirements
C) It tracks the cache memory usage for each process
D) It manages input/output operations for the system
Answer: A) It switches the CPU between different modes for executing instructions

Which of the following is an advantage of memory protection and privilege levels in modern computing?
A) Increased performance by reducing memory usage
B) Enhanced security by isolating processes and preventing unauthorized access
C) Simplified process management by allowing shared memory access
D) Improved speed of context switching
Answer: B) Enhanced security by isolating processes and preventing unauthorized access

Which of the following mechanisms allows a process to execute a system call while running in user mode?
A) The process switches to kernel mode temporarily
B) The system call is executed with user-mode privileges
C) The process gains unrestricted access to memory
D) The CPU bypasses the MMU
Answer: A) The process switches to kernel mode temporarily

Memory Protection and Privilege Levels MCQs
By: Prof. Dr. Fazal Rehman Shamil | Last updated: September 20, 2024

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