Microsoft cloud services were impacted late on Thursday 2 May after a Domain Name System (DNS) configuration error.

Between 19:43 and 22:35 UTC, Azure and other Microsoft services like M365, Dynamics, DevOps, and Xbox Live suffered connectivity issues.

Legacy issues

DNS Azure
– Twitter

"Engineers identified the underlying root cause as a nameserver delegation change affecting DNS resolution and resulting in downstream impact to Compute, Storage, App Service, AAD, and SQL Database services," Microsoft explained on its status page.

"During the migration of a legacy DNS system to Azure DNS, some domains for Microsoft services were incorrectly updated. No customer DNS records were impacted during this incident, and the availability of Azure DNS remained at 100 percent throughout the incident. The problem impacted only records for Microsoft services."

The company added: "To mitigate, engineers corrected the nameserver delegation issue. Applications and services that accessed the incorrectly configured domains may have cached the incorrect information, leading to a longer restoration time until their cached information expired."

The 'Service Health' page of Office 365 was also caught up in the outage, and was unable to detail the issue to 365 users.

Azure suffered a similar DNS-based outage as recently as this January, that time due to "a DNS issue with CenturyLink as an internal DNS provider."

Both outages pale in comparison to last year's much larger Azure outage, which brought systems down around the world for more than a day after lightning strikes took out the cooling in its San Antonio, Texas data center.