All.- We are in the process of changing our domain controller from DOMAIN-A (2008) to DOMAIN-B (2008). The plan is to migrate everything to DOMAIN-B and de-promote DOMAIN-A so it will not exist anymore after the migration. We have an Exchange 2010 and we know it is highly dependable on Active directory (domain controller) so we are wondering what will be the best approach to change our Exchange 2010 to our new domain DOMAIN-B. The only solution that we have thought of is to backup the mailboxes and then format the server, install the OS, install exchange again and restore the mailboxes. We are not sure if this is the best approach or if there are other solutions out there. Even the approach we have thought of, we are not sure the best way to do it. Any suggestions will be highly appreciated. Rgds

Hi, Without knowing any sizes and how many mailboxes you have there, I would suggest a cross forest migration. That's the correct way to go, and there are a lot of articles out there around it This can be done by using the native tools or 3rd part tools How many mailboxes? How much maildata?Jonas Andersson | Microsoft Community Contributor Award 2011 | MCITP: EMA 2007/2010 | Blog: http://www.testlabs.se/blog | Follow me on twitter: jonand82

Hello Jonas.- Thank you for your quick reply Jonas. He goes the answers: - Around 100 Mailboxes - Around 1-2 GB each mail box, so around 150 GB of data. Please keep in mind, we would like to have the same server on a different domain controller (active directory). We do not have another server to do the transition, so we either use the same server and backups of the mailboxes or just change the same server to another domain if possible. The method you are suggesting is what we use to upgrade from Exchange 2003 to Exchange 2010 just that they were on the same domain, but the cross forest migration I have seen assumes you will be either upgrading exchange or moving to another server which we do not have. Any more ideas?

I would seriously consider VMWare ESXi virtualization. Once you visualize, one server ( with decent memory ) can actually service the needs of at least 4 of your current servers. This approach will also allow you to snapshot a machine prior to an upgrade etc.... I know it's our of scope of your question, but if you doing DOMAIN - A to DOMAIN - B opperations I think you are large enough to tackle visualization first.