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How to force Exchange to authenticate to different DC

Last Modified: 2012-08-13
How do I force Exchange 2003 to authenticate to a different DC (Windows 2003).  Our DC is currently down, all other servers (IIS, SQL) are fine but Exchange is giving netlogon errors and the main services (MTA, Info Store etc) won't start.
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Presumably the exchange server is set to use the DC that is down for its DNS also. You need to male sure that another DC/DNS server is added as the alternate DNS server and that that DC/DNS server also holds a global catalog. On the second DC, go to Administrative Tools, Active Directory Sites and Services, Expand ,Sites, Default first site and Servers. Right click on the new server and select properties and tick the Global Catalog checkbox. (Global catalog is essential for logon as it needs to be queried to establish Universal Group Membership)

To make the Exchange server change DC you can either wait 35 minutes or try this (won't always work):
ESM: Properties for the Exchange server, tab Directory Access, select Domain Controllers in the drop-down list, select a working DC in the window and delesect Automatically discover servers.
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Presuming that the other server is a global catalog, restart the Exchange services. That will force Exchange to find another DC to use.



KCTS: there is no GC checkbox available to select.
peakpeak: I cannot deselect as the option is greyed out.
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Expert of the Year 2006

This is Microsoft's article on how to set a new Global Catalog.

It is important that you verify that there is another GC available as Exchange needs a GC to talk to. It will also impact your users ability to login to the domain.

If the resource kit utilities are loaded on the Exchange server you can also use the "nltest" utility to reset the secure channel to another domain controller.  However this DC must have a global catalog as stated above.  I forget the exact syntax but its comething like nltest /sc_reset:domain\domancontroller.

Use the /? switch to view the command's help.  You'll see the proper syntax to be used.
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