Your company has a main office and a branch office.
The network contains an Active Directory forest. The forest contains three domains. The
branch office contains one domain controller named DC5. DC5 is configured as a global
catalog server, a DHCP server, and a file server.
You remove the global catalog from DC5.
You need to reduce the size of the Active Directory database on DC5.
The solution must minimize the impact on all users in the branch office.
What should you do first?

A.
Start DC5 in Safe Mode.

B.
Start DC5 in Directory Services Restore Mode.

C.
On DC5, start the Protected Storage service.

D.
On DC5, stop the Active Directory Domain Services service.

Explanation:
http://allcomputers.us/windows_server/windows-server-2008-r2—manage-the-activedirectory-database-%28part-2%29—defragment-the-directory-database—audit-activedirectory-service.aspx
Windows Server 2008 R2 : Manage the Active Directory Database (part 2) – Defragment the
Directory Database & Audit Active Directory Service
3. Defragment the Directory Database
A directory database gets fragmented as you add, change, and delete objects to your
database. Like any file system–based storage, as the directory database is changed and
updated, fragments of disk space will build up so it needs to be defragmented on a routine
basis to maintain optimal operation. By default, Active Directory performs an online
defragmentation of the directory database every 12 hours with the garbage collection
process, an automated directory database cleanup, and IT pros should be familiar with it.
However, online defragmentation does not decrease the size of the NTDS.DIT database file.
Instead, it shuffles the data around for easier access. Depending on how much
fragmentation you actually have in the database, running an offline defragmentation—which
does decrease the size of the database—could have a significant effect on the overall size of
your NTDS.DIT database file.
There is a little problem associated with defragmenting databases. They have to be taken
offline in order to have the fragments removed and the database resized. In Windows Server
2008 R2, there is a great feature that allows you to take the database offline without shutting
down the server. It’s called Restartable Active Directory, and it could not be much easier to
stop and start your directory database than this. Figure 4 shows the Services tool and how
you can use it to stop the Active Directory service.
1. Start the Services tool from the Control Panel.
2. Right-click Active Directory Domain Services, and select Stop.

Figure 4. You can use the Services tool to stop and restart Active Directory.
That’s it! Now when you stop Active Directory Domain Services, any other dependent
services will also be stopped. Keep in mind that while the services are stopped, they cannot
fulfill their assigned role in your network. The really cool thing about Restartable AD is that
while the directory services and its dependent services are stopped, other services on the
local machine are not. So, perhaps you have a shared printer running on your DC. Print
services still run, and print operations do not stop. Nice!
3.1. Offline Directory Defragmentation
Now that you have stopped Active Directory services, it is time to get down to the business
of offline defragmentation of the directory database:
1. Back up the database.
2. Open a command prompt, and type NTDSUTIL.
3. Type ACTIVATE INSTANCE NTDS.
4. Type FILES, and press Enter.
5. Type INFO, and press Enter. This will tell you the current location of the directory
database, its size, and the size of the associated log files. Write all this down.
6. Make a folder location that has enough drive space for the directory to be stored.
7. Type COMPACT TO DRIVE:\DIRECTORY, and press Enter. The drive and directory are
the locations you set up in step 5. If the drive path contains spaces, put the whole path in
quotation marks, as in “C:\database defrag”.
A new defragmented and compacted NTDS.DIT is created in the folder you specified.
8. Type QUIT, and press Enter.
9. Type QUIT again, and press Enter to return to the command prompt.
10.If defragmentation succeeds without errors, follow the NTDSUTIL prompts.
11.Delete all log files by typing DEL x:\pathtologfiles\*.log where x is the drive letter of your
drive.
12.Overwrite the old NTDS.DIT file with the new one. Remember, you wrote down its
location in step 4.

13.Close the command prompt.
14.Open the Services tool, and start Active Directory Domain Services.
Defragmenting your directory database using the offline NTDSUTIL process can significantly
reduce the size of your database depending on how long it has been since your last offline
defrag. The hard thing about offline defrag is that every network is different, so making
recommendations about how often to use the offline defrag process is somewhat spurious. I
recommend you get to know your directory database. Monitor its size and growth. When you
think it is appropriate to defragment offline, then do it. A pattern will emerge for you, and you
will find yourself using offline defragmentation on a frequency that works well for your
network and your directory database. One of the cool things about offline defragmentation is
that if you should happen to have an error occur during the defragmentation process, you
still have your original NTDS.DIT database in place and can continue using it with no
problems until you can isolate and fix any issues.