We have 6 AD servers all running 2008 or 2008R2. We also have about 40 servers running a mix of 2003/2008 with 2 servers running 2000 and all are member servers. Our current domain functional level is 2003. I need to migrate to 2012 so I want to first raise our domain functional level to 2008 R2 and then incorporate 2012 DC's and raise it again.
The question is, can I do this without worrying about the Windows 2000 servers (as member servers) being able to authenticate users to the 2008R2 & beyond AD structure? I can't at this time upgrade or remove these servers as they are running a specific tool that is no longer supported and to replace it would cost ALOT of money.