Summary
This document is a post-mortem report detailing the incident that occurred on May 8th, 2026, when Quad9's primary zone, 'quad9.net', experienced a significant outage lasting approximately 40 minutes. The outage was attributed to a failed validation step between the primary hidden authoritative nameservers and the public anycast nameservers hosted by PCH. The root cause was linked to legacy configuration issues that were not adequately documented, which were inadvertently altered during recent maintenance. The timeline of the incident is outlined, starting from the first log of zone failures at 15:50 UTC, through the incident response efforts, to the full recovery confirmation at 16:45 UTC. The impact of the outage on users is also discussed, noting that while some users were unaffected, those attempting to access services under 'quad9.net' faced interruptions. Recommendations for future improvements in the authoritative nameserver configuration are also provided.
