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1. IL-0533 Names in chinacloudapp.cn and chinacloudsites.cn stopped resolving as DNS caches expired, breaking Azure China services

   Microsoft Azure2024

   Symptoms

   From 03:45 CST on 23 April 2024, FQDNs in two system domains of Azure in China, chinacloudapp.cn and chinacloudsites.cn, gradually stopped resolving, and customers in the Azure China regions had trouble connecting to many Azure services and managing resources. Internal monitors alerted engineers to the degradation at 04:37 CST.

   DNS resolution failuresHigh error rateMonitoring outage

   Trigger

   At 03:45 CST a configuration change made through a domain registrar, as a step of a domain decommissioning workflow, updated the nameservers of chinacloudapp.cn and chinacloudsites.cn to a set of inactive servers.

   Root cause

   Configuration change

   Component

   Authoritative DNS servers and records

   Contributing factor

   Unverified assumptionCache-masked failure

   Detection

   Internal monitors alerted engineers to the degradation in the Azure China Cloud at 04:37 CST and created an incident, which the engineering team acknowledged at 04:39 CST.

   Remediation

   • Reverted the two domains to their previous working nameservers

   Action items

   • Suspended further runs of the domain lifecycle process until the management tool covers Azure in China
   • Make the validation process of domain lifecycle management include signals from all cloud regions
   • Add validations that get nameserver information by resolving the zone directly over the Internet

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