1. What is the ways to infect the system by virus?
1.PEN DRIVES AND INTERNET
2.installing 3rd party softwaes
3.crack,patch,keygen
4.connecting in a lan where other computer's in that network
may contain viruses.
If two or more processes requests for a common resource
and which one does not find the resource is considered as
Waiting and the one occupied the resource is called as Busy.
NTLDR File may corrupt or deleted.
it is resolved by copying perticular file from bootable cd
from the foldet(I386) to the windoe's installed path(mostly
c:) .
OR
By repairing by recover operation .
4. Tell me What are the hardware problem you face regularly in your organization?
Its depends What are the device you have in your organisation.
Say for example if you have AD and Mail server and firewall.
The problem you may face more account locked if you have account lock policy, the account lock may cause mail access issues. And if you have firewall on your network the admin is restricting all unwanted traffic and etc then each folder access from one pc to other you may request him to allow.
5. What is the difference between NTFS & FAT File systems?
NTFS stands for new technology file system or network
technology file system. In NTSF partition size can be of 2
TB or more. and file size can be 16 TB. file/folder
encryption is done. and it supports file name character
upto 255.
FAT32 stands for File allocation table. in FAT32 partition
size can be Upto 2 TB. and file size can be 4 GB.
file/folder encryption is not possible in FAT32. and it
supports file name character upto 8.3.
6. What basically a system call is?
user programs cmmunicates with an o.s and request services
from it by system call.The purpose of system call is to
request the o.s to perform some task.every system call has a
library procedure that a user program call....
7. Where the system time is stored? In processor or in Separate timer ic for that?
System time is stored in seprate timer ic.
8. What is the operating system of mac?
macintosh, followed by Tiger and now its Lepord
1. reason - the control blocks for processes are larger
than for threads (hold more state information), so the
amount of information to move during the thread switching
is less than for process context switching
2. reason - the major reason is that the memory management
is much simpler for threads than for processes. Threads
share their memory so during mode switching, memory
information does not have to be exchanged/changed, pages
and page tables do not have to be switched, etc. This makes
the thread context switch much cheaper than for processes.
In case of processes the memory pieces (pages) need to be
exchanged, etc. (Will talk about the details in few weeks).
3. reason - threads do not have to worry about accounting,
etc, so do not have to fill out all the information about
accounting and other process specific information in their
thread control block, so keeping the thread control block
consistent is much faster
4. reason - threads share files, so when mode switch
happens in threads, these information stay the same and
threads do not have to worry about it (similar to
accounting information) and that makes the mode switch much
faster.
10. What is the difference among deadlock avoidance, detection and prevention?
revention:
• The goal is to ensure that at least one of the
necessary conditions for deadlock can never hold.
• Deadlock prevention is often impossible to
implement.
• The system doesnot require additional apriori
information regarding the overall potential use of each
resource for each process.
• In order for the system to prevent the deadlock
condition it does not need to know all the details of all
resources in existence, available and requested.
• Deadlock prevention techniques include non-blocking
synchronization algorithms, serializing tokens, Dijkstras
algorithm etc.
• Resource allocation strategy for deadlock
prevention is conservative, it under commits the resources.
• All resources are requested at once.
• In some cases preempts more than often necessary.
Avoidance:
• The goal for deadlock avoidance is to the system
must not enter an unsafe state.
• Deadlock avoidance is often impossible to
implement.
• The system requires additional apriori information
regarding the overall potential use of each resource for
each process.
• In order for the system to be able to figure out
whether the next state will be safe or unsafe, it must know
in advance at any time the number and type of all resources
in existence, available, and requested.
• Deadlock avoidance techniques include Banker's
algorithm, Wait/Die, Wound/Wait etc.
• Resource allocation strategy for deadlock avoidance
selects midway between that of detection and prevention.
• Needs to be manipulated until atleast one safe path
is found.
• There is no preemption.
Detection:
• The goal is to detect the deadlock after it occurs
or before it occurs.
• Detecting the possibility of a deadlock before it
occurs is much more difficult and is, in fact, generally
undecidable. However, in specific environments, using
specific means of locking resources, deadlock detection may
be decidable.
• The system doesnot requires additional apriori
information regarding the overall potential use of each
resource for each process in all cases.
• In order for the system to detect the deadlock
condition it does not need to know all the details of all
resources in existence, available and requested.
• A deadlock detection technique includes, but is not
limited to, Model checking. This approach constructs a
Finite State-model on which it performs a progress analysis
and finds all possible terminal sets in the model.
• Resource allocation strategy for deadlock detection
is very liberal. Resources are granted as requested.
• Needs to be invoked periodically to test for
deadlock.
• Preemption is seen.
