Kubernetes Interview Questions – Expert Scenario Based (20 Q&A)
This page provides expert-level Kubernetes interview questions covering cluster architecture, workloads, networking, storage, security, real-field failures and lab troubleshooting. These questions are designed for DevOps Engineers, SREs, Cloud Architects and Telecom professionals running cloud-native workloads.
Conceptual & Architecture Questions
Q1. Why is Kubernetes needed when Docker exists?
Docker manages containers on a single host, while Kubernetes orchestrates containers across multiple nodes, providing scaling, self-healing and service discovery.
Q2. Explain Kubernetes cluster architecture.
A Kubernetes cluster consists of control plane components (API server, scheduler, controller manager, etcd) and worker nodes running kubelet and container runtime.
Q3. What is a Pod in Kubernetes?
A Pod is the smallest deployable unit in Kubernetes and may contain one or more tightly coupled containers.
Q4. How does Kubernetes achieve high availability?
By running multiple replicas of workloads, distributing them across nodes and automatically replacing failed components.
Workload & Scheduling Scenarios
Q5. Why is a Pod stuck in Pending state?
Insufficient cluster resources, unsatisfied node selectors, taints/tolerations or missing persistent volumes.
Q6. How does Kubernetes scheduler decide Pod placement?
The scheduler evaluates resource availability, affinity rules, taints/tolerations and policies to place Pods optimally.
Q7. What happens when a node fails?
Pods running on the failed node are rescheduled on healthy nodes to maintain desired state.
Q8. How do you perform rolling updates?
Using Deployments with rolling update strategy to gradually replace old Pods with new ones.
Networking & Storage Scenarios
Q9. How does Kubernetes networking work?
Each Pod gets a unique IP; CNI plugins enable Pod-to-Pod communication across nodes.
Q10. Difference between ClusterIP, NodePort and LoadBalancer?
ClusterIP exposes services internally, NodePort exposes via node ports, and LoadBalancer integrates with external load balancers.
Q11. Why can’t Pods communicate across namespaces?
Network policies may restrict traffic; namespaces provide logical isolation.
Q12. How does Kubernetes handle persistent storage?
Using PersistentVolumes, PersistentVolumeClaims and storage classes to abstract underlying storage.
Security & Real Field Scenarios
Q13. How do you secure a Kubernetes cluster?
Use RBAC, network policies, Pod security standards, secrets management and regular patching.
Q14. What is RBAC and why is it important?
RBAC controls who can access or modify cluster resources, enforcing least privilege.
Q15. Why does application performance degrade in Kubernetes?
Resource limits, CPU throttling, noisy neighbors or inefficient networking can degrade performance.
Q16. How do you troubleshoot production Kubernetes issues?
Check Pod status, events, logs, metrics and node health using kubectl and monitoring tools.
LAB & Hands-On Scenarios
Q17. Pod keeps restarting – debugging steps?
Inspect container logs, health probes, resource limits and application startup behavior.
Q18. How do you test auto-scaling in Kubernetes?
Configure HPA, generate load and observe Pod scaling based on metrics.
Q19. Service is created but not accessible – why?
Incorrect selectors, missing endpoints, firewall rules or load balancer misconfiguration.
Q20. How do you design a Kubernetes stress test?
Simulate high traffic, Pod churn, node failures and scaling events while monitoring cluster stability.
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