D686 Practice Questions and Correct Answers for OA and
Pre-Assessment Prep – WGU D686 Latest Practice Test 2026
/ Operating Systems for Computer Scientists
300 Questions derived from the D686 book
What is the purpose of system utilities in an operating system?
Facilitating program development and execution
3 multiple choice options
Which operating system structure separates functionality into multiple layers?
Layered structure
3 multiple choice options
Which vulnerability can be exploited by malicious actors to gain unauthorized
access to operating systems?
Buffer overflows
3 multiple choice options
What is the primary purpose of asymmetric clustering in a clustered system?
To ensure one computer is always in hot-standby mode
3 multiple choice options
Which system service enables the operating system to interact with peripheral
hardware, such as disk drives and printers?
Device management
3 multiple choice options
What is the role of a process in a computer system?
Executing user and system tasks
3 multiple choice options
Which state is a process when it is paused and is not currently being executed?
pg. 1
,Waiting
3 multiple choice options
How does a context switch impact CPU performance?
It temporarily suspends the current process to switch to another.
3 multiple choice options
What is the purpose of scheduling queues in process management?
To manage the order of process execution
3 multiple choice options
What is the result of a fork() system call in Unix?
Creation of a child process
3 multiple choice options
Which mechanism allows processes to work together without interfering with each
other?
Communication through interprocess mechanisms
3 multiple choice options
Which method involves processes exchanging data by sending and receiving
messages?
Message passing
3 multiple choice options
How does synchronization ensure proper process execution?
By preventing simultaneous access to shared resources
3 multiple choice options
Which type of thread is managed directly by the operating system?
Kernel-level
3 multiple choice options
What is a significant advantage of using multithreading in applications?
pg. 2
,It increases responsiveness and resource sharing.
3 multiple choice options
What is the coordination of processes used to ensure they operate without
interfering with each other?
Synchronization
3 multiple choice options
What is a situation where the outcome of a process execution depends on the
specific order in which processes access shared data?
Race condition
3 multiple choice options
How can processes avoid race conditions in a multiprocessor environment?
By employing synchronization mechanisms
3 multiple choice options
Which mechanism ensures exclusive access to a critical section by allowing only
one process to enter at a time?
Mutex lock
3 multiple choice options
Which mechanism uses counters to control access to resources, allowing processes
to wait for availability and signal completion?
Semaphore
3 multiple choice options
Which type of semaphore behaves similarly to a mutex lock, allowing only one
process to access a critical section at a time?
Binary
3 multiple choice options
Which classic synchronization problem involves ensuring that multiple readers can
access shared data simultaneously but only one writer can modify it at a time?
pg. 3
, Readers-writers problem
3 multiple choice options
What does the dining philosophers problem illustrate in terms of synchronization?
The complexity of managing multiple resources among multiple processes
3 multiple choice options
Which synchronization construct encapsulates data and operations, ensuring
mutual exclusion and simplifying process synchronization management?
Monitor
3 multiple choice options
How does a monitor ensure that only one process can access shared data at a time?
By implementing condition variables
3 multiple choice options
What is the method used to determine which processes will be assigned to the CPU
for execution?
CPU scheduling
3 multiple choice options
How does a preemptive scheduling algorithm differ from a non-preemptive
scheduling algorithm?
Preemptive scheduling can interrupt a running process to assign the CPU to
another process.
3 multiple choice options
Which criterion measures the total time taken from the submission of a process to
its completion?
Turnaround time
3 multiple choice options
Which scheduling criterion aims to keep the CPU as busy as possible?
Utilization
pg. 4
Pre-Assessment Prep – WGU D686 Latest Practice Test 2026
/ Operating Systems for Computer Scientists
300 Questions derived from the D686 book
What is the purpose of system utilities in an operating system?
Facilitating program development and execution
3 multiple choice options
Which operating system structure separates functionality into multiple layers?
Layered structure
3 multiple choice options
Which vulnerability can be exploited by malicious actors to gain unauthorized
access to operating systems?
Buffer overflows
3 multiple choice options
What is the primary purpose of asymmetric clustering in a clustered system?
To ensure one computer is always in hot-standby mode
3 multiple choice options
Which system service enables the operating system to interact with peripheral
hardware, such as disk drives and printers?
Device management
3 multiple choice options
What is the role of a process in a computer system?
Executing user and system tasks
3 multiple choice options
Which state is a process when it is paused and is not currently being executed?
pg. 1
,Waiting
3 multiple choice options
How does a context switch impact CPU performance?
It temporarily suspends the current process to switch to another.
3 multiple choice options
What is the purpose of scheduling queues in process management?
To manage the order of process execution
3 multiple choice options
What is the result of a fork() system call in Unix?
Creation of a child process
3 multiple choice options
Which mechanism allows processes to work together without interfering with each
other?
Communication through interprocess mechanisms
3 multiple choice options
Which method involves processes exchanging data by sending and receiving
messages?
Message passing
3 multiple choice options
How does synchronization ensure proper process execution?
By preventing simultaneous access to shared resources
3 multiple choice options
Which type of thread is managed directly by the operating system?
Kernel-level
3 multiple choice options
What is a significant advantage of using multithreading in applications?
pg. 2
,It increases responsiveness and resource sharing.
3 multiple choice options
What is the coordination of processes used to ensure they operate without
interfering with each other?
Synchronization
3 multiple choice options
What is a situation where the outcome of a process execution depends on the
specific order in which processes access shared data?
Race condition
3 multiple choice options
How can processes avoid race conditions in a multiprocessor environment?
By employing synchronization mechanisms
3 multiple choice options
Which mechanism ensures exclusive access to a critical section by allowing only
one process to enter at a time?
Mutex lock
3 multiple choice options
Which mechanism uses counters to control access to resources, allowing processes
to wait for availability and signal completion?
Semaphore
3 multiple choice options
Which type of semaphore behaves similarly to a mutex lock, allowing only one
process to access a critical section at a time?
Binary
3 multiple choice options
Which classic synchronization problem involves ensuring that multiple readers can
access shared data simultaneously but only one writer can modify it at a time?
pg. 3
, Readers-writers problem
3 multiple choice options
What does the dining philosophers problem illustrate in terms of synchronization?
The complexity of managing multiple resources among multiple processes
3 multiple choice options
Which synchronization construct encapsulates data and operations, ensuring
mutual exclusion and simplifying process synchronization management?
Monitor
3 multiple choice options
How does a monitor ensure that only one process can access shared data at a time?
By implementing condition variables
3 multiple choice options
What is the method used to determine which processes will be assigned to the CPU
for execution?
CPU scheduling
3 multiple choice options
How does a preemptive scheduling algorithm differ from a non-preemptive
scheduling algorithm?
Preemptive scheduling can interrupt a running process to assign the CPU to
another process.
3 multiple choice options
Which criterion measures the total time taken from the submission of a process to
its completion?
Turnaround time
3 multiple choice options
Which scheduling criterion aims to keep the CPU as busy as possible?
Utilization
pg. 4
