<<Sharing the latest update from Azure Status page>>
Preliminary Root Cause: We are continuing to investigate the underlying cause for the DNS outage but we have observed that Microsoft DNS servers saw a spike in DNS traffic.
Mitigation: Microsoft engaged resilient DNS capabilities to absorb the spike in DNS traffic.
Next Steps: We apologize for the impact caused by this outage. We are continuing to investigate to establish the full root cause. For the latest status, please visit https://status.azure.com/en-us/status/history/
If you have further questions feel free to add them in the comments to this thread.