DNS Lookup Failures Due to Resource Limits

DNS lookup failures occurred due to resource limits on the CoreDNS pods.

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What Happened

CoreDNS pods hit their CPU and memory resource limits, causing DNS queries to fail intermittently.

Diagnosis Steps

1Checked CoreDNS logs and identified that it was consistently hitting resource limits.
2Verified that the node resources were underutilized, but CoreDNS had been allocated insufficient resources.

Root Cause

Insufficient resource limits set for CoreDNS pods.

Fix/Workaround

• Increased the resource limits for CoreDNS pods to handle the load.
• Restarted the CoreDNS pods to apply the new resource limits.

Lessons Learned

Always allocate sufficient resources for critical components like CoreDNS.

How to Avoid

1Set resource requests and limits for critical services based on actual usage.
2Use Kubernetes Horizontal Pod Autoscaler (HPA) to automatically scale resource allocation for CoreDNS.