Hi If you have one root domain and multiple child domains on your forest like below example. Root domain : rootdomain.com Child domain 1 : firstchild.com Child domain 2 : secondchild.com Child domain 3 : thirdchild.com When you install Exchange 2007 for the organization, do you install it under rootdomain.com? That way, all other child domains share those exchange servers? or Do you install them separately on each child domain? I prefer the first option, so there will be less number of Exchange servers, but is it possible? What do you recommend for such forest? Thank you for your help!