I'm only in the evaluation phase of Exchange 2010, but I'm trying to figure out how after a failover, how AD or Outlook know that your mailbox is located on a completely different server now. Are the days of actually specifying what server a person's mailbox should be stored on gone now? So, could someone describe the process of what happens after the failover? How does it affect the user who has a mailbox on the failed server? How long are they down?

Client Access Server would take care of that part.Nitin Gupta (gupnit) | MVP - Exchange | http://www.nitingupta.in/blogs

Review these : http://technet.microsoft.com/en-us/library/dd633496(EXCHG.140).aspxhttp://msexchangeteam.com/archive/2009/06/14/451609.aspxNitin Gupta (gupnit) | MVP - Exchange | http://www.nitingupta.in/blogs

I thought Client Access Server was only for " any user who opens their mailbox using Outlook Web Access, Exchange ActiveSync, POP3 or IMAP4" - at least it was that way in Exchange 07? So now, CAS knows where your mailbox is stored, and is automatically updated upon failover, and informs Outlook of the change? (Hopefully without restarting Outlook, like I've been reading about in other posts on DAG failover.) Thanks Nitin. I was writing that while you were submitting those links.

Yes, as Nitin said CAS will take care of new server info to outlook. Yes, in Exchange 2010 all type of clients (including MAPI/Outlook) are connecting now through CAS box to access mailboxes available on Mailbox Server...Amit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com

Hi Stormwriter,Here is the forum dedicated for Exchange 2010, you can write your questions there in the future. :)http://social.technet.microsoft.com/Forums/en-US/exchange2010/threadsThanks,Elvis