Dear Sir/Madam, I have 2 exchnge server 2007 server in head office. both contains Client access role, Hub Trans, mailBox Roles. I have one exchange server in Branch, which is exhange 2003 server and Bridgehead server.. I want to demote this Branch server and also want to install exchange server 2010 CAS, HT,Mailbox role server on single hardware.. Hardware is powerful... my strategy is following:- 1. I will transfer all the mailboxes from branch 2003 to exchange server 2010 in Head office. 2. Shutdown Branch server for two days.... 3. then demote the Branch exchange server 2003 and Reformat the server and will install windows 2008 R2 OS.... [ here I have doubts.. how I can demote this exchange 2003 server from AD schema and metadata all these information related to old exchange server 2003... I waill keep same name of physical machine.. then will it give any problem] 4. after formatting and intsall new exchange server 2010 server I will move all the same mail boxes from Head office to branch office. I hvae doubt here that is it possible to install 2010 on branch office without installing it in Headoffice.... 5. is it not give any problem if i dont change name of physical/exchange server 2010. 6. Our Branch AD server is 2003 server but rest of 2 server in HO is windows 2008 R2 server.... 7. After Successfull Migration of this I will go for Head office migration but that is latter .. may be for next week.... your help will be very needful for me as it is very critical system in our organization.... Thanks in dvance Thanks & Regards, Vishal Sharma

You cannot run DCPROMO on a machine that is running Exchange. You should also remove Exchange correctly using add/remove programs, rather than just wiping the machine. Therefore if you want to upgrade the machine you will need to: 1. Migrate all data off. 2. Uninstall Exchange 2003 correctly. 3. DCPROMO the machine to a member server. 4. Rebuild the machine. 5. If you want the machine to be a domain controller, then you should DCPROMO it before installing Exchange. However, be aware that in most circumstances it is not recommended to install Exchange on a domain controller and certainly not in a multiple site/server deployment. When Exchange is installed on a DC, all other Exchange servers will only use that DC for their functionality, so you may see a performance hit - unless ALL other Exchange servers are installed on a domain controller. If you want to install Exchange 2010 in to a site with Exchange 2007 then all other Exchange 2007 servers must be at Exchange 2007 SP3 level and it will need to make schema changes. You should also ensure that you have your sites and services configured correctly. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.