Not sure which forum would be best for this question, but since the problem started with my new iphone 6 on IOS 8, I'll give it a shot here. I have used Gmail contacts, calendar and mail since my Droid days. Got an iphone 4 and used Exchange to synch to the phone. It's all worked correctly (even iphone 5, though I know I read it should not after Google stopped supporting it) until I restored to my new iPhone 6. No Gmail came through. And the contacts did not appear to be updating. So I set my Gmail and Contacts up through the Google option instead. It all seems to be working. (Left calendar on exchange because it's synching perfectly on phone, ipads and Macs for whatever reason) But then I saw the option for CardDav. How is this different from the synch I am doing through the Google link under Settings > Mail, Contacts, Calendars? If CardDav is a must, why is it working with Google? Thanks for your insight.