“Proof of domain ownership has failed” Exchange Hybrid Configuration Wizard Failure – if you are seeing this error even after your DOMAIN VERIFICATION / OWNERSHIP Status is OK in #Office365 you may need to do some extra effort. There are many articles related for the same problem but they all have different or similar scenario but not exactly. So I cam across a TechNet article the other day (I’ve followed many other blogs too) and there one simple step you need to make sure you copy the current TEXT for the Domain Proof.
Let say your Federation Trust keep on failing then you need to follow this
at the Exchange Shell run this
copy all the proof text ending with ==
and create a new Text Record for that domain- Now if you run the wizard again it will run successfully