DNS & Service Discovery Interview Questions

Why DNS & Service Discovery Matters in Interviews

DNS is the glue that holds Kubernetes networking together. Without it, every application would need to track IP addresses manually — an impossibility in a dynamic environment where Pods are created and destroyed constantly.

Interviewers frequently ask you to explain how a Pod resolves a Service name, walk through the full DNS query path from the application through the resolv.conf search domains to CoreDNS, and describe what records exist for different Service types. You should know the difference between a ClusterIP Service DNS record that returns one virtual IP and a headless Service record that returns multiple Pod IPs. Expect troubleshooting scenarios: a Pod cannot resolve a Service name in another namespace, DNS queries are slow because ndots is set too high, or CoreDNS Pods are in CrashLoopBackOff. Candidates who can explain the Corefile configuration, customize DNS behavior per Pod, and set up external-dns for automatic public DNS management show the depth of knowledge teams need for operating production Kubernetes clusters.