Exchange 2007 (also a DC) to Exchange 2013 migration

Hi,

I'm planning for a migration and was looking for any advice anyone may have based on their experiences. Here is our existing setup:

• One Exchange 2007 (all roles on one box, and its on a Windows 2003 DC; this is not SBS)
• Two  Windows 2003 DCs (as per above, as you can tell the need for this migration)

The goal is to:

• Introduce a new dedicated Exchange 2013 server (as a VM)
• Introduce 2 new Windows 2012R2 DCs (both physical)

I'm aware that the Exchange has to be at least SP3 for coexistance. From the compatibiltiy list it shows that Windows 2003 DCs are supported.

Should I make the 2012 R2 servers the DCs before installing Exchane 2013? The part I'm not quite sure about is how to go about this since Exchange is running on the 2003 DC and if it will break anything by trying to make another.

bl