Top 20 Kubernetes Interview Questions & Answers (Short & Sweet)

If you're preparing for a Kubernetes interview, here are the most common questions with crisp, to-the-point answers. Save this cheat sheet!

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1. What is Kubernetes?

Answer: Container orchestration platform for automating deployment, scaling, and management.

2. Difference between Docker Swarm and K8s?

Answer: Swarm is simpler, integrates with Docker; K8s is complex, feature-rich, auto-healing, and scales better.

3. What are Pods?

Answer: Smallest deployable units; one or more containers sharing network/storage.

4. What is a ReplicaSet?

Answer: Ensures a specified number of pod replicas run at all times.

5. Deployment vs StatefulSet?

Answer: Deployment for stateless apps; StatefulSet for stateful (stable network ID, persistent storage).

6. What does a Service do?

Answer: Exposes pods as network services with stable IP and load balancing.

7. Ingress vs LoadBalancer?

Answer: LoadBalancer: L4, cloud LB; Ingress: L7, HTTP routing to multiple services.

8. What is a ConfigMap?

Answer: Stores non-sensitive config data as key-value pairs for pods.

9. How to handle secrets?

Answer: Use Secret objects (base64 encoded, not encrypted by default) + RBAC.

10. What is etcd?

Answer: Distributed key-value store storing all cluster state/data.

11. Difference between kubectl apply and create?

Answer: create works only on new resources; apply creates/updates declaratively.

12. What is a Namespace?

Answer: Virtual cluster for resource isolation/quota.

13. How does kube-scheduler work?

Answer: Assigns pods to nodes based on resource reqs, affinity, taints, etc.

14. What are taints and tolerations?

Answer: Taints repel pods; tolerations let pods ignore specific taints.

15. How to debug a crash-looping pod?

Answer: kubectl logs <pod> --previous, kubectl describe pod, check probes/liveness.

16. Difference between liveness and readiness probes?

Answer: Liveness: restart container on failure; Readiness: stop sending traffic.

17. What is a DaemonSet?

Answer: Runs one pod per node (e.g., logging, monitoring).

18. How to upgrade a deployment without downtime?

Answer: RollingUpdate strategy; kubectl set image deployment/<name> <container>=<new>.

19. What is a PersistentVolume (PV) and PVC?

Answer: PV: cluster storage; PVC: pod's request for storage.

20. What is Helm?

Answer: Package manager for K8s (charts = templated K8s manifests).

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Bonus Tip: Practice with kubectl explain command during the interview!