Unresponsive External API Due to DNS Resolution Failure

External API calls from the pods failed due to DNS resolution issues for the external domain.

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What Happened

DNS queries for an external API failed due to an incorrect DNS configuration in CoreDNS.

Diagnosis Steps

1Checked CoreDNS logs and found that DNS queries for the external API domain were timing out.
2Used nslookup to check DNS resolution and found that the query was being routed incorrectly.

Root Cause

Misconfigured upstream DNS server in the CoreDNS configuration.

Fix/Workaround

• Corrected the upstream DNS server settings in CoreDNS.
• Restarted CoreDNS pods to apply the new configuration.

Lessons Learned

Proper DNS resolution setup is critical for communication with external APIs.

How to Avoid

1Regularly monitor CoreDNS health and ensure DNS settings are correctly configured.
2Use automated health checks to detect DNS issues early.