We are investigating a problem with Azure Active Directory authentication services worldwide. Customers are reporting failing authentication when attempting to sign on to web applications and when requesting tokens for access to the Graph API. Next update in one hour.
UPDATE: Mitigation steps have been taken and recovery started at about 9:03PDT. Recovery will take some time as changes to DNS propagate throughout DNS caches.
UPDATE 2: We believe we are now fully recovered. We will posting an update to the forum shortly on what occurred.