How to safely change the domain controllers that Exchange use from Out-Of-Site into the In-Site ?

Hi Folks,

I'd like to know what's the best way to edit the Exchange Server 2007 entry In-Site entries and removing the entries from Out-Of-Site safely without causing any downtime or problem with the workstations ?

From the MSExchange ADAccess Event ID 2080, I can see that the Domain Controllers that is currently used by Exchange Servers is all on theIn-Site lists which I need to decommission due to office building migration and downsizing, the workstations remain in the same building only the servers must go.

Current configuration:

Exchange Servers AD Site: HQ1 (for all roles)
Workstations AD Site: HQ1

Proposed configuration:

Exchange Servers AD Site: Prod-DC1 (for all roles)
Workstations AD Site: HQ1

Thanks.

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