Our Network Admin had demoted old 2007 DC and forced new DC (2013) IP address to all servers. Problem 1: CAS servers in the DMZ did not pickup new IP's. Problem 2: Barracuda spam appliance did not pickup new DC IP's. Problem 3: no one can connected with their Outlook client and fails at Autodiscover. The few clients that were previously connected (like myself) are able to still connect.
It seems this DNS change has wreaked havoc in the Exchange environment. In the meantime I am upgrading to CU3 as it is forcing me to re-install RSAT tool for Active directory preparation.