Question : Replace Windows 2003 DC with a new Windows 2008 DC


Basically we have two sites and both sites have 2 domain controllers. I am looking to replace DC at one site, which is the main DC with FSMO roles and DNS. I have bought a new server with Windows 2008 for the replacement, but need to keep the existing DC name and IP address for the new server. Also need to transfer DNS and DHCP from old server to new one and then plan to demote old server. But need to make sure everything is ok, before demote the old DC and can any experts give good instructions for this please?


Answer : Replace Windows 2003 DC with a new Windows 2008 DC

The process is as follows

First you need to Adprep your 2003 Domain by running
adprep /forestprep    and
adprep /domainprep   and
adprep /gpprep

from the 2008 DVD on the Windows 2003 DC  - adprep is in the SOURCES folder on the DVD.

Next install 2008 server on the new machine. You need to assign the 2008 new computer a different name and IP address to the other machines for the moment.

Make sure that the preferred DNS server on new machine points to the existing DNS Server on the Domain (normally the existing domain controller)

Join the new 2008 machine to the existing domain as a member server

From the command line promote the new machine to a domain controller with the DCPROMO command from the command line Select "Additional Domain Controller in an existing Domain"

Once Active Directory is installed then to make the new machine a global catalog server, go to Administrative Tools, Active Directory Sites and Services, Expand, Sites, Default first site and Servers. Right click on the new server and select properties and tick the"Global Catalog" checkbox. (Global catalog is essential for logon as it needs to be queried to establish Universal Group Membership) - This should be the deafult for server 2008 anyway - but check

Install DNS on the new server. Assuming that you were using Active Directory Integrated DNS on the first Domain Controller, DNS will automatically replicate to the new domain controller along with Active Directory. Set up forwarders as detailed at

You must transfer the FSMO roles to the 2008 machine then the process is as outlined at

You then need to install DHCP on the new 2008 server and set up a scope, activate it and authorize the server.

Change all of the clients (and the new 2008 DC itself), to point to the 2008 DC for their preferred DNS server this may be in DHCP options or the TCP/IP settings.

You can then transfer any data to the new server

Before removing the old DC from the domain, run DCPROMO on it to remove Active Directory.

Once the old server has been removed form the network then you can rename the 2008 DC and chnage its IP address to that of the server it has replaced - then run DCDIAG /fix to force an update of the DC information.
(you may need to install the support tools to install DCDIAG - they are on the CD/DVD)

Netometer has a nice video -
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