Microsoft cloud outage caused by DNS blunder

Microsoft blamed a DNS configuration error for the three-hour outage

Microsoft Azure users were unable to access the cloud service on Wednesday, after a DNS configuration blunder caused an outage.

Yesterday, heaps of users from across the world were unable to connect to a plethora of Microsoft cloud services for several hours as a result of a DNS issue.

The outage impacted a range of Microsoft services, including Azure databases, Microsoft 365, Teams, Dynamics, OneDrive, SharePoint Online and Compute services.

Following reports of the flaw, Microsoft posted an Azure status page saying: 'Customers may experience intermittent connectivity issues with Azure and other Microsoft services (including M365, Dynamics, DevOps, etc).

'Engineers are investigating DNS resolution issues affecting network connectivity. Connectivity issues are resulting in downstream impact to Compute, Storage and Database services, and some customers may be unable to file support requests.

'More information will be provided as it becomes available. Some customers may start to see recovery.'

After investigating the outage, Microsoft confirmed that 'users may be unable to access Microsoft 365 services or features'.

The firm explained that 'affected services include SharePoint Online, OneDrive for Business, Microsoft Teams, Stream, Power BI, Planner, Forms, PowerApps, Dynamics 365, Intune and Office Licensing'.

Microsoft said it had 'identified and corrected a DNS configuration issue that prevented users from accessing Microsoft 365 services and features'.

It continued: 'We've observed an increase in successful connections and our telemetry indicates that all services are recovering. We're continuing to monitor the environment to validate that service has been restored.'

The three-hour outage has since come to an end, with Microsoft confirming that its engineers had resolved the problem and that most services have been recovered.

'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,' it said.

'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% throughout the incident. The problem impacted only records for Microsoft services.

'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.'