I know, I'm a few months late, but I am finally getting started on my Server 2003 migration project.
I currently have 2 domain controllers running on our domain with Server 2003 and a funtional/forest level of 2003. I also already have the 2 new Server 2012 domain controllers built out joined to the domain, but I haven't promoted them to domain controllers yet.
My main concern, is that my primary DC is also serving DHCP to clients on our network and it's also the primary internal DNS server as well as NTP. The new Server 2012 domain controller will also serve these same roles. All of our current servers DNS address and applications using NTP are pointing to the IP address of our primary DC. How should I handle this without having to reconfigure every server, desktop, laptop, application, etc on our network?
DC01 - 10.0.0.10 - Primary DC (Server 2003)
DC02 - 10.0.0.20 - Backup DC (Server 2003)
DC03 - 10.0.0.50 - Primary DC (Server 2012)
DC04 - 10.0.0.60 - Backup DC (Server 2012)
All in all, I need DC03 and DC04 to consume the DC01/DC02 IP addresses once the cut-over happens. Are there certain steps I should go about doing this? Once I transfer all of the FSMO roles and DC01 and DC02 are demoted, can I simply take them offline and reset the NICs on DC03/DC04 to their addresses? Any other caveats I should worry about from doing this?
Thanks for all of the help in advance. This my first DC upgrade, so it will go a long in helping me get the process down.