Operating Systems c191

What is an operating system (OS)?

Software that runs on bare hardware.

Which type of CPU instruction sets are supported by the CPU user mode?

Only non-privileged

What are two locations where firmware can be stored?

Flash Memory and Read-only Memory (ROM)

Which generation of computers were large-scale integrated circuits used to develop personal computers for desktop and laptop operating systems?

4th

A company requires a computing environment that supports high-volume data processing and the management of a large amount of storage.

Which computing environment should the company use?

Mainframe

What is a system service?

An application included with an operating system to provide functionality beyond the kernel

A company needs to determine when a computer experiences a microprocessor interrupt that is the result of a division by zero.

Which operating system (OS) service should be used?

Error detection

Which interface allows combining multiple programs using the output from one as the input to another?

Command-line Interface (CLI)

Which command is used to determine the number of lines within a file?

wc

Which cyberattack prevents a legitimate user from accessing an application in a timely manner?

Denial-of-service

Which operating environment is used to run an embedded system?

Real-time

What is a thread?

Part of a process that can run concurrently with other parts

What are the two properties of threads?

1. Using multiple threads within a process is more efficient than using multiple processes

2. User-level threads are faster to manage than kernel-level threads

Which component is responsible for running and suspending tasks in a multitasking operating system (OS)?

Process manager

Which resource is virtualized by multitasking?

Processor

Which technique is used to execute several jobs by time-sharing among them?

Multitasking

What is a computer program in execution called?

Process

What is the relationship between threads, processes, and global data?

All threads within a process share the same copy of global data

What does each thread of a multi-threaded process use to access shared code?

Program counter

What is a critical section?

An area of code that cannot be entered by a process while another process is executing a corresponding area of the code.

How do threads differ from processes?

Threads execute portions of a program within a process.

Which scheduler is used to decide the ready process that should run next in the CPU?

Short-term

A process is not attempting to enter the critical section (CS), but is preventing other processes from entering the CS.

Which situation was caused by this process?

Lockout

Which step is completed first during an input/output (IO) call?

The process is placed on the wait queue.

Which free memory space management strategy allocates the smallest free partition that meets the requirement of the requesting process?

Best-fit

Which method does the operating system use to divide system memory into contiguous, equal-sized partitions?

Paging

What is the physical memory size for an address size of 8 bits?

256

What causes a page fault?

Present bit as to 0

What should be used to improve memory until ozark on when loading external references?

Dynamic linking

Why are approximations used in place of the least-recently-used (LRU) algorithm?

Higher efficiency

What describes the 50% rule in external memory fragmentation?

1/3 of memory may be lost.

What describes the differences between internal and external fragmentation?

External fragmentation occurs with memory blocks at variable sizes, and internal fragmentation occurs at fixed sizes.

What does the memory manager do that can lead to poor performance?

It is unable to allocate contiguous free blocks as needed and or is forced to compact memory to fulfill allocation both causing processes to wait.

What are two effects of lagging in the address space?

It permits the physical address of a process to be noncontiguous and divides the logical address space of a process into equal-sizes partitions.

What is a page in memory management?

Fixed-size contiguous block of logical address space insecticide by a single number.

What is used to determine the number of processes that can run concurrently?

Load control

What are two measures of positioning time?

Moving the disk arm to the desired cylinder and rotating the desired sector to the disk head

A company needs to ensure consistent performance by decreasing the density of bits from inner tracks to outer tracks?

Which hard disk method should be used?

Constant angular velocity

Which disk type provides direct access to a secondary storage device as an array of blocks with no file system?

Raw

What is the advantage of swapping?

Allows computers to execute more processes than there is available physical memory on a computer

Which file attribute should be used to identify who can access a file?

Protection

Which scheduling system should be used to stop a process that is currently running and select another process to run?

Preemptive

Which data structure represents the allocation status of each disk block?

Bitmap

Which latency waits for the requested data to pass under the drive head if a magnetic hard disk?

Rotational delay

What is the determining factor for sustained throughput in magnetic storage?

Data transfer rate

What can be used to access Dropbox?

Application programming interface (API)

What is a direct memory access (DMA) controller?

Hardware device allowing access of main memory without the CPU

What is partitioning?

Creating groups of blocks on secondary storage

Which user authentication method has the form of a dialogue between user and system?

Challenge-response

What provides asymmetric cryptography?

Rivest-Shamir-Aldeman (RSA)

What is a symmetric key algorithm?

Data encryption standard (DES)

How to find the shortest capability list of an access matrix?

Count the least amount of entries within a row Di

How do you find the shortest access list in a access matrix?

Count the shortest amount of access modifiers within a cell.

Which two techniques guard against unauthorized activities when running code written by others?

Sandboxing and interpretation

What is a key that is used by a recipient to decrypt a message encrypted with asymmetric encryption?

Private

What is the benefit of asymmetric cryptography?

No need to exchange secret keys

When should digests be used?

Establishing an undeniable link between the document and its sender

Which technique involves requesting an unsuspecting user to disclose their credit card information on a fake website that looks legitimate?

Phishing

Which technique is used to bypass user authentication?

Backdoor

Which cyberattack technique is mitigated by using the CTRL+ALT+DLT key sequence in the Windows operating system?

Login spoofing