How does Windows Server 2008 resolve Domain Controller Load Balancing problems
The DC Locator Service has been re-designed in Windows Server 2008 to include a new mechanism. When a client computer finds a preferred domain controller, it sticks to this domain controller unless that domain controller stops responding or the client computer is restarted. This is generally called Domain Controller Stickiness. If you take this domain controller offline for maintenance purpose or it goes down, the clients that were connected to it will look for another domain controller to shift their connections to new domain controller. But when the domain controller comes online again, these connections are not shifted back because client computers do not refresh themselves to check to see if domain controller is back again. This can cause load-balancing issues because client computers remain connected to same domain controller.
Windows Server 2008 includes a new Group Policy setting for client computers. If a domain controller goes down and whenever the DC Locator Service invokes itself to execute the DcGetDCName API call, it retrieves a domain controller name from its cache. It checks to see if this cached entry is expired. If it is expired, it discards this domain controller and tries to search a new domain controller for the client. To enable this Group Policy for client computers, navigate to the following location using Group Policy editor:
Location: Administrative Templates\System\Net Logon\DC Locator DNS Records\ Entry Name: Force Rediscovery Interval.
Values: The default value is 12 hours. The minimum value is 1 hour The maximum value is 49 days.