The original configuration was a single server running HT, CAS & MB.I have instaleld a 2nd server into another AD site as HT, CAS & MB.So we are now runnign 2 severs both running HT, CAS & MB.After doing this it appers that 2nd server has automatically been configured as the OAB web-based distribution server for the entire org!Why would this happen?What cuases this to change over autmatically?Would this also cause all Outlook clients to resync thier OAB with the new exchnage server?Thanks,Steve

HiWhat version clients you are using ? OAB distributing Public Folders ?

Hi, First please check event log to see if you have any error event logged on CAS1(CAS in the first site). Please try to delete the OAB from \Exchange\ClientAccess\OAB and then restart the Exchange File Distribution Service on the CAS server it will copy the files over from the Mailbox server to \ExchangeServer\ClientAccess\OAB\<OABGrid>. After that, please try to logon the first site and then try to use Test e-mail autoconfiguration to check the OABurl. How Exchange 2007 OAB Files are replicated to a Client Access Server for download http://blogs.msdn.com/dgoldman/archive/2006/08/25/How-Exchange-2007-OAB-Files-are-replicated-to-a-Client-Access-Server-for-download.aspx Regards, Xiu

Thank you Xiu. Your insight helped me solve an issue I had with Exchange 2010 where the GAL/OAB was not updating. I think it started after removing a role (unified messaging). After much head banging I found the Microsoft Exchange File Distribution service was set to disabled and stopped. From my limited understanding of this, the Microsoft Exchange File Distribution service is critical to copying/updating the GAL to the OAB. I found the files in C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\OAB\GUID were stale and not being updated. Enabling/starting the Microsoft Exchange File Distribution service fixed the issue and updated the OAB. Your instructions led me in the right direction.