Issue due to DDoS attack on our DNS provider, DynDNS:
https://www.dynstatus.com/incidents/5r9mppc1kb77
Summary:
On 21-Oct-2016, our DNS service provider reported an issue of temporary DNS unavailability. More details available on provider page.
Impact: during daily monitoring, Sitecore's Cloud Operations indicated a very few instances of unavailability of our services like xDB Cloud Discovery Service (used in xDB Cloud 1.0) and App Center services for short period of times during 21-Oct.
Resolution: all systems fully available and stable since 22-Oct.