Professional OS General Concepts Interview Questions & Answers:

1. Explain in which situation we use sjf scheduling algorithm?

when we want to reduce the average waiting time in non
preemitive sjf and response time in pree,tivesjf or srtf

2. In general what is paging? and segmaentation?

Paging is the memory mgmt scheme that permits the physical
address space of a process to be non contigous.Pages are of
fix sizes.

Segmentationis the memory mgmtscheme that consider adrees
space as collectionof segments. Segments are o0fvariable sizes.

3. How to install operating system through USB pen drive?

For creating a bootable USB drive with Windows 2000 or XP
installer we are going to use a utility called
WinSetupFromUSB. Download it from MSFN forums and install
it. You are going to need the Windows 2000/XP installation
disk. If you have an ISO, extract the iso. Enter the path to
Windows 200/XP installer as Source. After this, plugin in
your USB device and format it. You can use the PEtoUSB tool
to format USB drives smaller than 2GB as FAT16 drive.
However I would recommend using HP Format Tool to format
drives as FAT32 or NTFS (recommended). That is all you need
to do to create a basic installer for Windows 2000 and
Windows XP on your pen drive (USB device). Don't bother
yourself with any of the other settings. Click on GO to
begin the process. WinSetupFromUSB is a fairly advanced tool
and allows to you create multiboot pen drives that can have
Windows Vista, Windows 7 and even Linux installers. If you
want to know more about this utility just read through the
thread at MSFN forums.

4. What are multi core operating systems?

It's a single processor system in which the processor is
divided into more than one parts(core)

5. What is virtual memory?
How we can increase or decrease the virtual memory?

Virtual memory are a part of operating sysytem in which
whenever ram have no space to execute any process than
operating system uses some part of hard disk as a ram.
Those part of memory known as virtual memory because this
is virtually created by operating system whenever needed.
This memory created by operating system in big companies in
which more process executes and ram have no space because
they contain more process already. Most operating systems
contains this concept.

6. What is the full form of "windows xp"?

XP = Extrme Performance

7. Who was the discover Mouse and When?

Douglas Engelbart in the year 1963

8. What is batch programming in DOS?

Batch programming is creating a file with DOS commands which will execute
with a single click even if it comprises of thousands of DOS commands. It's much faster than manual execution of commands. And saves the effort of retyping the same commands over and over again if you're doing a repetitive job with a fixed set of commands. You can rather type those commands down in notepad, save the file as filename.bat as an "all files" type of file. For example if there are a set of services to start on 100 systems, it's a waste of time going to each system, and starting all the services manually. You can type down commands to start those services, save it as a batch file, and run this batch file on all the systems.
All the services will start with just a click.

9. Suppose we have one root domain & two child domain, then in total how many FSMO roles i will have in entire forest?

My answer is 11 roles.
5 roles for root domain,
3 roles for one child domain &
3 roles for 2nd child domain.

10. Explain What is the difference between Authoritative restore & Non-Authoritative restore?

A nonauthoritative restore is the default method for
restoring Active Directory. To perform a nonauthoritative
restore, you must be able to start the domain controller in
Directory Services Restore Mode. After you restore the
domain controller from backup, replication partners use the
standard replication protocols to update Active Directory
and associated information on the restored domain
controller.

An authoritative restore brings a domain or a container back
to the state it was in at the time of backup and overwrites
all changes made since the backup. If you do not want to
replicate the changes that have been made subsequent to the
last backup operation, you must perform an authoritative
restore. In this one needs to stop the inbound replication
first before performing the An authoritative restore.