Replacing a Primary Domain Controller

Abstract

In general having one or more Backup Domain Controllers (BDC) is a good idea. However, that is not always practical. At times, you will encounter a situation where you must replace the existing Primary Domain Controller (PDC); perhaps to upgrade the existing hardware. This checklist should help you with the required steps.

Replacing a PDC

The Basics

Install your new hardware;
Install Windows NT on the new machine, and configure it as a BDC for the domain;
- Make your boot device the same as on the PDC ( ie. "C:" or "D:" );
- Name your system root the same as on the PDC ( ie. "\WINNT" or "\WINNT35" );
  This will help you in migrating other services.
Installing as a BDC results in the user and security databases being replicated from the PDC to the BDC (albeit in Read Only form).
Once complete, start Server Manager and select the newly added BDC, then choose "Promote to Primary Domain Controller" from the "Computer" menu (See below):

This will synchronize the user/security databases between the two and configure the BDC as the read/write copy and transfer the PDC responsibility to it.

Next, the Other Stuff ...

Software that uses the JET database engine ...

JET databases (examples include WINS and DHCP) have encoded into them the full path to the data. Therefore, products that you want to move from the PDC to the new machine (which fall into this category) will have to be installed onto the same device letter and into the same directory as on the old PDC( eg. for DHCP the directory is: C:\WINNT\SYSTEM32\DHCP ).

WINS

You may or may not wish to restore WINS since WINS will re-build its databases over time anyway. If like us you have a complex web of WINS replication configured, it saves time to restore WINS.

DHCP

DHCP is more important than WINS in that you cannot have a backup DHCP server replicating your DHCP data. Items such as active leases will evaporate (causing users some consternation - and by definition, therefore, your helpdesk too!). DHCP therefore is best copied from you existing server.

Moving this data ...

install the relevent services ( DHCP and/or WINS ) while configuring TCP/IP on your new server, but ensure that the services are NOT running;
stop DHCP and/or WINS on the old PDC (eg. NET STOP DHCP);
copy the service data files from the old PDC to the new machine ( eg. for DHCP: C:\WINNT\SYSTEM32\DHCP\*.* )
start DHCP and/or WINS on the new machine (eg. NET START DHCP);

If you have any other services, 3rd party or MS, you will have to refer to the documentation for that software to determine if you can just copy it or if you will have to re-install it or as above, some grizzly combination of the two.

[BabinszkiWorld] [WinNT] [Chinchillas] [Net Distiller] [Search] [More] [e-mail Andy Babinszki] 12-Jun-1996