Microsoft Active Directory Topology Diagrammer

Totally useful diagraming tool!!! It requires you to have Visio as well.
Get tool here from Microsoft

Time sync with external NTP on windows server 2008 R2 DC

1. Locate PDC - C:\>netdom /query fsmo
2. Log in to PDC Server and open the command prompt.
3. Stop the W32Time service: C:\>net stop w32time
4. Configure the external time sources, type: C:\> w32tm /config /syncfromflags:manual /manualpeerlist:”0.pool.ntp.org, 1.pool.ntp.org, 2.pool.ntp.org”
5. Make your PDC a reliable time source for the clients. Type: C:\>w32tm /config /reliable:yes
6. Start the w32time service: C:\>net start w32time
7. The windows time service should begin synchronizing the time. You can check the external NTP servers in the time configuration by typing: C:\>w32tm /query /configuration
8. Check the Event Viewer for any errors.

NOTE: Make sure your firewall allows NTP out before you do this or your DC will not be able to contact outside NTP servers.

Demoting DC fails with RPC error

I was recently demoting an old domain controller and go an RPC error message that looked like "The RPC server is unavailable". This was that much more undesirable error as everything was ok with DNS and all controllers were communicating with each other with no problem.

Rather simple solution resolved my problem.

1. open sites and services on a DC that is not being demoted
2. Navigate to DC that is not being demoted
3. Select NTDS Settings under that server
4. In the right pane select DC you are demoting, right click and choose Replicate now. You should see "Active directory has replicated the connections." If you do not see such message you probably have some AD or DNS issues.
5. Perform dcpromo on server you are demoting again.