DNS Latency Due to Overloaded CoreDNS Pods

CoreDNS latency increased due to resource constraints on the CoreDNS pods.

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What Happened

CoreDNS started experiencing high response times due to CPU and memory resource constraints, leading to DNS resolution delays.

Diagnosis Steps

1Checked CoreDNS pod resource usage and found high CPU usage.
2Verified that DNS resolution was slowing down for multiple namespaces and services.
3Increased logging verbosity for CoreDNS and identified high query volume.

Root Cause

CoreDNS pods did not have sufficient resources allocated to handle the query load.

Fix/Workaround

• Increased CPU and memory resource limits for CoreDNS pods.
• Restarted CoreDNS pods to apply the new resource limits.

Lessons Learned

CoreDNS should be allocated appropriate resources based on expected load, especially in large clusters.

How to Avoid