OWA and Outlook RPC URLs
A question came up at Exchange Connections this past week about using a separate name space for the OWA/Web Services/ActiveSync URL than you use for the RPC Client Access area. eg...
Microsoft recommends keeping these separate. While it *does* work if they both point to the same hostname and/or IP address, if they are separate, you reduce the risk of external Outlook clients (Outlook Anywhere / RPC over HTTP) timing out.
Here is the text from TechNet: