Monday, 7 September 2020

How to point a client to different Domain Controller


When a logon request is made to a domain, the workstation sends out a request to find a domain controller for the domain. The domain name is actually a NetBIOS name that is a 16-character name with the 16th character used by Microsoft networking services to identify the NetBIOS type.

For some reason some clients are not working as expected or working slower and you want to point client to different domain controller. To find out if any of the domain controllers is having problems you can quickly change the domain controller that the affected client is using.

Back in the day when Windows NT 4 ruled the world there was a command called setprfdc (set preferred domain controller) nltest does something similar.

So first we wanted to find out what DC the client is using. Now there are many different ways but here is a command that generally used:

nltest /dsgetdc:domain.local

The output was:

DC: \\DC1.DOMAIN.local
Address: \\
Dom Guid: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
Dom Name: DOMAIN.local
Forest Name: DOMAIN.local
Dc Site Name: Default-First-Site-Name
Our Site Name: Interxion
The command completed successfully.

This means that the client is using DC1. Now we wanted quickly to point the client to a different domain controller DC2. To do that write the following command:

nltest /Server:client0 /SC_RESET:domain.local\dc2

The output was:  

Flags: 30 HAS_IP  HAS_TIMESERVTrusted DC Name \\DC1.DOMAIN.local
Trusted DC Connection Status Status = 0 0x0 NERR_Success
The command completed successfully

 If you run the first command again you should see that domain controller has changed.

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