Preparation to demoting a DC

Posted on 2012-09-08
Last Modified: 2012-09-09

I have 3 DCs (2x Win 2008 R2 DC and 1x Win 2003 Ent DC). I am going to demote Win 2003 DC from the environment. I have moved all master roles long time ago. To understand if everyting alright, I have shutdown Win 2003 DC this morning (did not demote yet, just to simulate).

Exchange 2010 server's EMC start having difficulties to find DC. After a couple of try eventually EMC succesfully connected  to one of Win 2008 R2 DCs.
Outlook 2010 conneting to server with delay.
OWA had given Server busy try later error for a while but now it is OK.

Beside of above issues I haven't noticed any other problem yet.

I will keep the Win 2003 DC off for a week. According to symptoms above what shoudl I do? Why Exchange Server acting like that and what should I do to repevent future problem while demoting the Win 2003 DC.

Question by:teomcam
    LVL 22

    Expert Comment

    Do you have all of your DNS clients pointed to the W2008 DCs?  Before I demote a DC, I normally run NetMon to see what kind of traffic is going to that DC before shutting it down/demoting it...
    LVL 95

    Assisted Solution

    by:Lee W, MVP
    Exchange picks a Global Catalog Server to use... if that server is unavailable, then it can cause issues for a short period until it locates another.  Make sure your other DCs are Global Catalogs and you should be fine.

    Additional information
    LVL 8

    Author Comment

    Thanks guys. My other 2 Win 2008 R2 DCs are Global Catalog already. At the moment everything seems fine except Outlook 2010 connecting with a little delay.

    Could you give me syntax for netmon please so I can check what exactly going on.

    Is there any way to tell the Exchange server preferred DC?
    LVL 58

    Accepted Solution

    >> Is there any way to tell the Exchange server preferred DC?

    Yes. The Set-ExchangeServer cmdlet in the Exchange Management Shell allows you to statically configure the Domain Controllers which a particular Exchange 2010 server should bind to and use for AD lookups.

    See for details.

    But, I would not advise that you take those steps. It is NOT a best practice to hard-code the DCs and GCs into Exchange in this manner. In an otherwise healthy Active Directory environment, Exchange is more than capable - in fact, it is designed - to discover the topology of the network and automatically locate the appropriate Domain Controllers to use for service requests. Hard-coding should never be performed permanently without good cause.


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