DNS Resolution Failure

Interview Question

Your services suddenly cannot resolve domain names, breaking connectivity to dependencies. Walk me through your triage.

Key Points to Cover

Evaluation Rubric

Validates DNS resolution directly30% weight

Checks DNS service health/config30% weight

Considers temporary resolver fallback20% weight

Proposes long-term monitoring20% weight

Hints

Common Pitfalls to Avoid

⚠️**Assuming the scope immediately:** Jumping to conclusions about the cause without first determining the scope (e.g., one pod vs. all pods vs. all hosts).
⚠️**Neglecting to check local configuration:** Overlooking `resolv.conf` or equivalent settings on the client side and focusing solely on the server.
⚠️**Ignoring network connectivity:** Assuming network paths are clear to DNS servers without explicit verification (e.g., firewalls, routing).
⚠️**Failing to correlate with recent changes:** Not checking deployment logs or configuration history, which often reveals the trigger.
⚠️**Not testing both internal and external resolution:** Focusing only on external domains while missing issues with internal service discovery.

Potential Follow-up Questions