This is a very interesting blog post put together by Tom Shinder regarding a mysterious interaction they found regarding Outlook RPC/HTTP behavior when the computer was configured as a DirectAccess client. It seems that Outlook was looking at the link detection speed for the IP-HTTPS adapter instead of the link speed of the actual NIC, and then made a decision to use that link speed to determine whether or not to use RPC/HTTPS instead of MAPI/RPC.
Another interesting discussion was related to issues of an active IP-HTTPS adapter on an IPv4 only network, and how that might affect DA client behavior when a Network Location Server was not reachable.
Check it out at:
DEBRA LITTLEJOHN SHINDER
MVP (Enterprise Security)