Our organisation has two Exchange 2007client access servers (single site)configured with the below roles: Ex01: Hub transport, client access, Mailboxes Ex02: client access Ex02 is used for OWA. It seems that when some clients on the internal network open up certain calendar meetings (specifically with external invitees)or update the address book, they are directed to Ex02. Up until installing a SAN certificate with both external and internal domain names on Ex02, this was throwing up a certificate error. The SAN certificate has sorted the certificate error and is now allowing access to EX02 without the error. I am still confused as to why the internal Outlook clients would be trying to resolve calendar data from Ex02. Calendar data is stored in the mailbox in 2007 so I would have thought these requests would have been directed to the Exchange server hosting the mailboxes and not just any client access server in the site. I would appreciate any info on how this setup should work and how the Outlook client selects a client access server. Thanks Loz

Hi, I would like to explain that for Outlook 2007, it retrieves Free/Busy information, download OAB files through CAS server. Therefore, pleas check whether the issue also occurs if you use Outlook 2003. For internal Outlook, Outlook first searches for a Service Connection Pointer (SCP) in Ad. The SCP contains the URL to the AutoDiscover service. If more than on SCP object is found in AD this means there are multiple CAS servers in the Exchange organization. When Outlook find more than one SCP object from various locations, it sorts the list of available SCPs by the Site= keyword that match the site the Outlook client is located in. At the top of the list are the SCP entries that are in the same site as Outlook client so Outlook chooses one to use to obtain the Autodiscover URL. Then, your Outlook clients send the request to Autodiscover service to obtain other URLs for Available service, OAB service. For the next process, you can refer to following article: The Autodiscover Service and Outlook Providers - how does this stuff work? http://msexchangeteam.com/archive/2008/09/26/449908.aspx When, if and how do you modify Outlook Providers? http://msexchangeteam.com/archive/2008/09/29/449921.aspx Mike