Kubernetes Interview Questions and Answers for 2 years experience

1. What is Kubernetes?

   • Answer: Kubernetes is an open-source container orchestration platform designed to automate, scale, and manage containerized applications across a cluster of hosts. It provides a framework for deploying, scaling, and managing applications without needing to manually provision and manage servers.

2. Explain the core components of Kubernetes.

   • Answer: Key components include: Master Nodes (Control Plane): etcd (key-value store), kube-apiserver (API), kube-controller-manager (manages resources), kube-scheduler (assigns pods to nodes), cloud-controller-manager (cloud integration). Worker Nodes: kubelet (agent on each node), kube-proxy (network proxy).

3. What is a Pod in Kubernetes?

   • Answer: A Pod is the smallest and simplest unit in the Kubernetes object model that you create or deploy. It represents a running process, typically a single container, but can also include multiple containers sharing resources and a network namespace.

4. What is a Deployment in Kubernetes?

   • Answer: A Deployment ensures that a specified number of Pod replicas are running. It manages updates and rollbacks, ensuring high availability and zero downtime deployments.

5. What is a Service in Kubernetes?

   • Answer: A Service provides a stable IP address and DNS name for a set of Pods. This allows applications to communicate with each other even if Pods are constantly being created and destroyed.

6. Explain different types of Kubernetes Services.

   • Answer: Common types include ClusterIP (internal cluster access), NodePort (external access via node IPs), LoadBalancer (cloud provider managed load balancer), Ingress (external access via Ingress controller).

7. What is a Namespace in Kubernetes?

   • Answer: Namespaces provide a way to logically separate resources within a single Kubernetes cluster. This allows for isolation between different teams or projects.

8. What are ConfigMaps and Secrets in Kubernetes?

   • Answer: ConfigMaps store configuration data as key-value pairs, while Secrets store sensitive information like passwords and API keys. Both allow you to manage configuration and sensitive data separately from your application code.

9. Explain Kubernetes Persistent Volumes (PVs) and Persistent Volume Claims (PVCs).

   • Answer: PVs represent storage that is available for use by Pods. PVCs are requests for storage by Pods. They are used to provide persistent storage that survives Pod restarts and even node failures.

10. What are Kubernetes Ingress controllers?

    • Answer: Ingress controllers manage external access to services in a Kubernetes cluster, typically providing features like load balancing, SSL termination, and routing based on hostnames or paths.

11. Describe the different scheduling strategies in Kubernetes.

    • Answer: Kubernetes offers various scheduling strategies, including default scheduling (based on resource constraints), priority-based scheduling (using priorities and weights), and more sophisticated strategies that can be implemented with custom controllers.

12. What are Kubernetes Jobs and CronJobs?

    • Answer: Jobs run to completion, ideal for batch processing. CronJobs schedule Jobs to run periodically, useful for recurring tasks.

13. Explain Kubernetes DaemonSets.

    • Answer: DaemonSets ensure that a single instance of a Pod is running on each node in the cluster. Useful for system-level daemons or agents.

14. What are StatefulSets in Kubernetes?

    • Answer: StatefulSets manage stateful applications that require persistent storage and stable network identities. They guarantee that Pods are recreated with the same identity after restarts or failures.

15. What is a Kubernetes Node?

    • Answer: A Node is a worker machine in the Kubernetes cluster. It runs the kubelet, kube-proxy, and containers.

16. Explain how Kubernetes handles node failures.

    • Answer: Kubernetes monitors the health of nodes. If a node fails, the kubelet on the node stops reporting its status, and the kube-controller-manager detects the failure. It then reschedules any Pods that were running on that node to other healthy nodes.

17. What is a Kubernetes ReplicaSet?

    • Answer: ReplicaSets ensure a specified number of Pods are running. They're often used as a building block for Deployments, but can be used independently.

18. How do you manage Kubernetes resources?

    • Answer: Using the `kubectl` command-line tool, you can create, update, delete, and manage Kubernetes resources such as Deployments, Services, and Pods. You can also use various Kubernetes dashboards and APIs for management.

19. Explain the concept of Kubernetes Labels and Selectors.

    • Answer: Labels are key-value pairs attached to Kubernetes objects. Selectors allow you to filter and select objects based on their labels. This enables sophisticated organization and management of resources.

20. What are Kubernetes annotations?

    • Answer: Annotations are similar to labels, but are meant for human-readable information and are not used by the Kubernetes system for automated operations.

21. What are the different ways to deploy applications to Kubernetes?

    • Answer: Common methods include using `kubectl apply -f`, Helm charts, and various CI/CD pipelines.

22. What is Helm?

    • Answer: Helm is a package manager for Kubernetes. It allows you to define, install, and manage complex applications easily using charts, which are templates for Kubernetes resources.

23. Explain Kubernetes network policies.

    • Answer: NetworkPolicies allow you to control network traffic between Pods within a Kubernetes cluster, enhancing security and isolation.

24. How do you troubleshoot issues in a Kubernetes cluster?

    • Answer: Troubleshooting involves using `kubectl describe` and `kubectl logs` commands, checking the Kubernetes events, examining node status, and analyzing resource utilization.

25. What are Kubernetes resource limits and requests?

    • Answer: Resource limits define the maximum amount of resources a container can use, preventing resource exhaustion. Resource requests specify the minimum amount of resources a container needs to function properly.

26. Explain the concept of Kubernetes liveness and readiness probes.

    • Answer: Liveness probes check if a container is still running and healthy. Readiness probes check if a container is ready to accept traffic. These probes help Kubernetes manage the health and availability of Pods.

27. What are the benefits of using Kubernetes?

    • Answer: Benefits include automated deployment, scaling, and management of containerized applications; improved resource utilization; high availability and fault tolerance; and simplified operations.

28. What are some common Kubernetes security best practices?

    • Answer: Best practices include using RBAC (Role-Based Access Control), limiting resource access, regularly updating Kubernetes components, scanning images for vulnerabilities, and implementing network policies.

29. How do you monitor a Kubernetes cluster?

    • Answer: You can use tools like Prometheus, Grafana, and Datadog to monitor resource utilization, application performance, and overall cluster health.

30. What are some common challenges encountered when working with Kubernetes?

    • Answer: Challenges include managing complexity, troubleshooting issues, ensuring security, optimizing resource utilization, and learning the ecosystem of tools and technologies.

31. Explain the concept of Kubernetes autoscaling.

    • Answer: Autoscaling automatically adjusts the number of Pods running based on resource utilization or other metrics, ensuring optimal performance and resource efficiency.

32. How do you handle secrets securely in Kubernetes?

    • Answer: Use Kubernetes Secrets to store sensitive data, avoid hardcoding credentials in application code, leverage external secret management tools, and ensure proper access control using RBAC.

33. What is the difference between a rolling update and a blue/green deployment?

    • Answer: Rolling updates gradually replace old Pods with new ones, minimizing downtime. Blue/green deployments have two environments (blue and green) running concurrently. Traffic is switched from blue to green after the green deployment is validated.

34. What is a PodDisruptionBudget?

    • Answer: A PodDisruptionBudget limits the number of Pods in a ReplicaSet, StatefulSet, or Deployment that can be deleted at any given time, ensuring high availability during upgrades or maintenance.

35. Explain how to manage different versions of your application using Kubernetes.

    • Answer: Use Deployments with image tagging, manage versions with Helm charts and semantic versioning, and leverage GitOps principles for version control and automation.

36. What are some common metrics to monitor in a Kubernetes cluster?

    • Answer: CPU and memory utilization, network traffic, disk I/O, pod restarts, and application-specific metrics are commonly monitored.

37. Describe your experience with troubleshooting Kubernetes network issues.

    • Answer: [Describe specific scenarios and how you resolved them, focusing on techniques like checking network policies, examining kube-proxy logs, using `kubectl describe` on Pods and Services, analyzing network connectivity with tools like `ping` and `traceroute`, etc.]

38. How have you utilized Kubernetes to improve application performance and scalability?

    • Answer: [Provide specific examples, focusing on how you used horizontal pod autoscaling (HPA), resource limits and requests, efficient deployment strategies like rolling updates, etc.]

39. Describe your experience with setting up and managing Kubernetes clusters.

    • Answer: [Explain your experience with different Kubernetes distributions like Minikube, Kubeadm, Rancher, GKE, AKS, EKS, etc. Detail any automation scripts or tools you used.]

40. How do you manage the lifecycle of a Kubernetes resource?

    • Answer: Using `kubectl apply`, `kubectl delete`, and related commands. Also discuss how you handle updates, rollbacks, and resource cleanup.

41. What are your preferred methods for securing a Kubernetes cluster?

    • Answer: [Explain your approach to security, encompassing RBAC, pod security policies/pod security contexts, network policies, secret management, image scanning, and regular security audits.]

42. How do you handle storage in Kubernetes for stateful applications?

    • Answer: Using Persistent Volumes (PVs) and Persistent Volume Claims (PVCs), discussing different storage classes and their implications.

43. Explain your understanding of different container registries and how they integrate with Kubernetes.

    • Answer: [Discuss Docker Hub, private registries, and how image pulling and deployment are handled in Kubernetes. Consider mentioning image signing and security practices.]

44. What are some best practices for designing and managing Kubernetes manifests?

    • Answer: [Discuss topics like using version control, using templating engines like Helm, employing structured YAML, creating reusable components, and adhering to naming conventions.]

45. How do you approach debugging complex issues in a large Kubernetes cluster?

    • Answer: [Detail your systematic approach, mentioning tools and techniques for analyzing logs, tracing requests, isolating problems, and using monitoring dashboards.]

46. What are your experiences with different Kubernetes monitoring tools?

    • Answer: [Share your experience with specific tools like Prometheus, Grafana, Datadog, etc. Describe how you've used them to monitor cluster health and application performance.]

47. How do you ensure high availability and disaster recovery for applications running on Kubernetes?

    • Answer: [Discuss strategies like multiple availability zones, using geographically distributed clusters, implementing backups and restores, and leveraging tools for disaster recovery.]

48. Describe your familiarity with different cloud providers' managed Kubernetes services.

    • Answer: [Share your knowledge of GKE, AKS, EKS, and other managed Kubernetes offerings. Highlight any differences in setup, management, or features.]

49. How do you integrate Kubernetes with your CI/CD pipeline?

    • Answer: [Describe your experience using tools like Jenkins, GitLab CI, CircleCI, etc., to automate building, testing, and deploying applications to Kubernetes.]

50. What are some common anti-patterns to avoid when using Kubernetes?

    • Answer: [Discuss issues like over-provisioning resources, neglecting resource limits, insufficient monitoring, ignoring security best practices, and using overly complex deployments.]

51. Explain your experience with Kubernetes operator patterns.

    • Answer: [Describe your knowledge of operators and how they simplify the management of complex applications. Mention any specific operators you've used.]

52. How familiar are you with Istio or other service mesh technologies?

    • Answer: [Share your experience with Istio or other service meshes, focusing on their role in managing service-to-service communication, security, and observability.]

53. How would you handle a scenario where a Kubernetes pod keeps crashing?

    • Answer: [Outline a methodical debugging approach, starting with checking logs, examining resource limits, investigating events, and inspecting probes.]

54. Explain your understanding of Kubernetes resource quotas.

    • Answer: Resource quotas limit the amount of resources (CPU, memory, storage, etc.) that can be consumed by a namespace, preventing resource exhaustion and ensuring fairness.

55. What is your experience with using kubectl?

    • Answer: [Provide specific examples of kubectl commands you've used, highlighting your proficiency in managing Kubernetes resources.]

56. How would you optimize the performance of a Kubernetes deployment?

    • Answer: [Discuss various optimization techniques, focusing on areas like resource allocation, image optimization, network configuration, and efficient pod design.]

57. Explain your understanding of the Kubernetes API server.

    • Answer: [Discuss its role as the central control point for managing Kubernetes resources, handling requests, and enforcing authorization.]

58. What are your thoughts on using GitOps for managing Kubernetes deployments?

    • Answer: [Discuss the advantages of GitOps, such as improved version control, automation, and observability, along with your experience implementing it.]

59. How do you stay up-to-date with the latest Kubernetes features and best practices?

    • Answer: [Mention resources like Kubernetes documentation, blogs, conferences, online communities, and relevant newsletters.]

60. Describe your experience working with Kustomize.

    • Answer: [Explain your understanding and use of Kustomize for customizing Kubernetes manifests without templating or modifying base YAML files.]

61. Explain how to troubleshoot a situation where pods are not receiving traffic.

    • Answer: [Detail your troubleshooting strategy, covering aspects like verifying service definitions, checking endpoints, ensuring readiness probes pass, and examining network policies.]

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