Client's Current Environment:
* Windows 2008 SP2 (not R2) running in 2003 mode. Empty Root with 3 child domains (We'll call them Child1, Child2, Child3)
* Exchange 2010 SP1
Exchange is installed in Child1. All user accounts with Exchange mailboxes reside in Child1.
I've noticed that some of the default DCs and GCs for all Exchange servers point to DCs/GCs in Child1, Child2 or Child3. I could have one HT server's primary DC be in Child3 and the other HT's primary DC be in Child1. I may have a mailbox server with a primary DC residing in the root.
I know that the preferred list is auto-generated by the Exchange Topology service which tells me that I may have a sites/subnets issue?
I've noticed that the DCs closest to Exchange are slammed (CPU >80% at all times) so is Exchange falling back to lesser utilized DCs?
What is the additional overhead (if any) by making LDAP queries against a DC/GC in Child3 or the root when all accounts reside in Child2?
Besides the client upgrading to R2 and Exchange updates (that's a given), what would be the best place to dive in and see what's going on?
As always, thanks for any and all assistance!