We have two sites which are two separate forests with separate Exchange organizations. We'll call them site A and site B as well as forest A and forest B. We want to unify the Exchange Organizations into one Exchange 2010 organization. We will use forest B as the account and exchange resource forest. Forest A will be a account forest only and use forest B as exchange forest for their mailboxes. Site A and Site B are connected by a T1. How many domain controllers should I have at site A for to authenticate the users with the exchnage forest in site B. if the link goes down between the sites I don't users to continue to be able to authenicate at both sites.

Hi Maybe you should start with reading through this http://www.msexchange.org/articles_tutorials/exchange-server-2007/planning-architecture/deploying-exchange-resource-forest-part1.html If there are any questions, just shoot :) Jonas Andersson MCTS: Microsoft Exchange Server 2007/2010 | MCITP: EMA 2007/2010 | MCSE/MCSA Blog: http://www.testlabs.se/blog

Okay but as far as the DCs needed to support the Exchange forest environement do you need two dcs or would one be enough?

I think you should always have two DCs configured as GCs for every domain. -- Ed Crowley MVP "There are seldom good technological solutions to behavioral problems." . "2010" wrote in message news:39e59bea-671d-4d1c-ac5f-cce62e611db0... Okay but as far as the DCs needed to support the Exchange forest environement do you need two dcs or would one be enough? Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

By the way, this is a strong reason to not create multiple domains. -- Ed Crowley MVP "There are seldom good technological solutions to behavioral problems." . "2010" wrote in message news:39e59bea-671d-4d1c-ac5f-cce62e611db0... Okay but as far as the DCs needed to support the Exchange forest environement do you need two dcs or would one be enough? Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

because of the added cost and management?

That's one of them, yes. -- Ed Crowley MVP "There are seldom good technological solutions to behavioral problems." . "2010" wrote in message news:f58ba3f1-b535-4ade-9102-c3f22cb1e07d... because of the added cost and management?Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Well our company has been lving with multiple two domains for ten years because how the company is organized. I would like to move towards one forest but I thought if we could segregate exchange environment into separate forest and then later move accounts to one forest. The exchange project is seen as more urgent so this will be tackled first. Theit will be easier to move acount and resources over later as exchange will already be taken care of and mailboxes can be relinked to new accounts forest.

If you put Exchange in a "resource forest" you still have to create user accounts for every mailbox hosted in that forest. With trusts in place, the user domains can authenticate to the resource domain, so this can be made to work. But it does add substantial administrative complexity. -- Ed Crowley MVP "There are seldom good technological solutions to behavioral problems." . "2010" wrote in message news:248f836a-c26a-4815-9057-bde3b30dae6d... Well our company has been lving with multiple two domains for ten years because how the company is organized. I would like to move towards one forest but I thought if we could segregate exchange environment into separate forest and then later move accounts to one forest. The exchange project is seen as more urgent so this will be tackled first. Theit will be easier to move acount and resources over later as exchange will already be taken care of and mailboxes can be relinked to new accounts forest. Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

“A small organization using a single local area network (LAN) might need only one domain with two domain controllers for high availability and fault tolerance. A larger organization with many network locations will need one or more domain controllers in each site to provide high availability and fault tolerance” ----------Refer to <Domain controllers> Determining the Minimum Number of Domain Controllers Required The question is more related to windows server area, please use “Windows server” forum which would be the best place for the questionJames Luo TechNet Subscriber Support (http://technet.microsoft.com/en-us/subscriptions/ms788697.aspx) If you have any feedback on our support, please contact tngfb@microsoft.com

Will do. Thanks