Degraded DNS performance on Cloud Resolvers

A recent upgrade of our resolvers to a new version on our Cloud Resolvers introduced a latency regression on Amsterdam node, degrading its DNS resolution performance. Other upgraded nodes experienced only very light slowdowns. The remaining nodes were not upgraded, so they were not affected.

Impact

• Ultra-fast replies (< 1 ms) fell by ~3 pp and slower replies (> 1 s) rose by ~1 pp, causing noticeable query delays.
• Only customers using Cloud Resolvers or Home Office Security were affected.

Resolution
We reverted the affected resolvers to the previous version. DNS resolution metrics returned to baseline within minutes.

Next Steps

• Conduct a root-cause analysis of the new version changes that led to the latency increase
• Enhance pre-deployment performance tests to catch similar regressions.
• Schedule a controlled re-release of the fixed resolver version once validated.