DNS Resolution Failure Due to CoreDNS Pod Crash

DNS resolution failed across the cluster after CoreDNS pods crashed unexpectedly.

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What Happened

CoreDNS pods were crashed due to resource exhaustion, leading to DNS resolution failure for all services.

Diagnosis Steps

1Used kubectl get pods -n kube-system to check the status of CoreDNS pods.
2Found that CoreDNS pods were in a crash loop due to memory resource limits being set too low.

Root Cause

CoreDNS resource limits were too restrictive, causing it to run out of memory.

Fix/Workaround

• Increased memory limits for CoreDNS pods.
• Restarted the CoreDNS pods and verified DNS resolution functionality.

Lessons Learned

Ensure CoreDNS has sufficient resources to handle DNS queries for large clusters.

How to Avoid