Kubernetes Interview Questions and Answers for internship

1. What is Kubernetes?

   • Answer: Kubernetes is an open-source container orchestration system for automating deployment, scaling, and management of containerized applications. It groups containers that make up an application into logical units for easy management and discovery.

2. Explain the key concepts of Kubernetes: Pods, Deployments, Services, and Namespaces.

   • Answer: Pods are the smallest deployable units in Kubernetes, containing one or more containers. Deployments manage the desired state of a set of Pods. Services provide a stable IP address and DNS name for a set of Pods. Namespaces provide a way to logically separate resources within a cluster.

3. What is a Kubernetes cluster?

   • Answer: A Kubernetes cluster is a set of machines (nodes) that run Kubernetes. It includes a control plane (master nodes) that manages the cluster and worker nodes (also known as minion nodes) that run the applications.

4. What are the different types of Kubernetes nodes?

   • Answer: Typically, there are master nodes (control plane) and worker nodes. Master nodes run the control plane components, while worker nodes run the Pods.

5. Explain the role of the Kubernetes control plane.

   • Answer: The Kubernetes control plane manages the cluster state, schedules Pods to nodes, and ensures that the desired state of the cluster is maintained. Key components include the kube-apiserver, kube-scheduler, and kube-controller-manager.

6. What are Kubernetes labels and selectors?

   • Answer: Labels are key-value pairs that can be attached to Kubernetes objects. Selectors are used to filter objects based on their labels. They are crucial for managing and organizing resources.

7. What is a Kubernetes Deployment?

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

8. What is a Kubernetes Service?

   • Answer: A Service provides an abstraction layer over a set of Pods, providing a stable IP address and DNS name. It allows communication with Pods regardless of their location or lifecycle.

9. Explain different types of Kubernetes Services (ClusterIP, NodePort, LoadBalancer, ExternalName).

   • Answer: ClusterIP creates a service accessible only within the cluster. NodePort exposes the service on each Node's IP at a static port. LoadBalancer creates an external load balancer (cloud-provider specific). ExternalName maps the service to an external DNS name.

10. What is a ConfigMap in Kubernetes?

    • Answer: A ConfigMap allows you to store configuration data as key-value pairs and inject it into Pods as environment variables or volume mounts.

11. What is a Secret in Kubernetes?

    • Answer: A Secret stores sensitive information like passwords, API keys, and certificates securely. It's similar to a ConfigMap but designed for sensitive data.

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

    • Answer: PVs are storage units provided by the cluster administrator, while PVCs are requests by applications for storage. They ensure persistent storage for applications even if Pods are restarted or rescheduled.

13. What are Kubernetes Ingresses?

    • Answer: Ingresses provide a way to expose HTTP services externally, often using a load balancer or reverse proxy. They simplify external access to applications running in the cluster.

14. What is a Kubernetes Namespace?

    • Answer: A Namespace provides a way to logically separate resources within a cluster. It's like a virtual cluster within a cluster.

15. Explain Kubernetes RBAC (Role-Based Access Control).

    • Answer: RBAC is a mechanism for controlling access to Kubernetes resources. It uses Roles and RoleBindings (or ClusterRoles and ClusterRoleBindings) to define permissions and assign them to users or groups.

16. What is a Pod lifecycle in Kubernetes?

    • Answer: A Pod goes through phases like Pending, Running, Succeeded, Failed, and Unknown during its lifecycle. These phases reflect the Pod's state and its containers' state.

17. How does Kubernetes handle scaling?

    • Answer: Kubernetes handles scaling by adjusting the number of replicas defined in Deployments, StatefulSets, or other controllers. It automatically creates or deletes Pods to match the desired replica count.

18. Explain Kubernetes rolling updates.

    • Answer: Rolling updates gradually replace old Pod replicas with new ones, minimizing downtime and ensuring a smooth transition. Deployments often use rolling updates.

19. What are StatefulSets in Kubernetes?

    • Answer: StatefulSets manage stateful applications that require persistent storage and stable network identities. They ensure that Pods maintain their identity across restarts or reschedulings.

20. What are DaemonSets in Kubernetes?

    • Answer: DaemonSets ensure that a single instance of a Pod is running on each Node in a cluster. They are useful for tasks like logging or monitoring that need to run on every node.

21. What are Jobs and CronJobs in Kubernetes?

    • Answer: Jobs run a specified number of Pods to completion. CronJobs schedule Jobs to run periodically, according to a cron expression.

22. What is a Kubernetes Pod Disruption Budget (PDB)?

    • Answer: A PDB limits the number of Pods that can be simultaneously deleted in a Deployment or StatefulSet, preventing large-scale disruptions.

23. Explain Kubernetes network policies.

    • Answer: Network policies control communication between Pods within a cluster. They allow you to define rules for ingress and egress traffic, enhancing cluster security.

24. How do you monitor Kubernetes clusters?

    • Answer: Kubernetes clusters can be monitored using tools like Prometheus, Grafana, and the Kubernetes dashboard. These tools provide insights into resource usage, application health, and cluster performance.

25. What are some common Kubernetes troubleshooting techniques?

    • Answer: Common techniques include using `kubectl describe` and `kubectl logs` to examine Pod and resource details, checking events for errors, and examining cluster logs.

26. What are the differences between Kubernetes and Docker?

    • Answer: Docker is a container runtime that creates and manages containers. Kubernetes orchestrates and manages clusters of containers and the nodes that host them. Docker is a tool; Kubernetes is a platform.

27. What are some popular Kubernetes distributions?

    • Answer: Popular distributions include Rancher Kubernetes Engine (RKE), Amazon Elastic Kubernetes Service (EKS), Google Kubernetes Engine (GKE), and Azure Kubernetes Service (AKS).

28. What are Helm charts?

    • Answer: Helm charts are packages of Kubernetes resources that simplify deployment and management of applications. They provide a templating mechanism for customizing deployments.

29. Explain the concept of "kubectl".

    • Answer: Kubectl is the command-line tool used to interact with the Kubernetes API server. It's essential for managing and interacting with Kubernetes resources.

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

    • Answer: Applications can be deployed using various methods such as kubectl apply, Helm, and CI/CD pipelines.

31. What is the role of a service mesh in Kubernetes?

    • Answer: A service mesh provides a dedicated infrastructure layer for managing service-to-service communication within a microservices architecture in Kubernetes. It handles tasks like traffic management, security, and observability.

32. Explain the importance of resource limits and requests in Kubernetes.

    • Answer: Resource limits and requests define the maximum and minimum resource allocation (CPU, memory) for Pods. They help prevent resource starvation and ensure fair sharing of resources across the cluster.

33. What are some security best practices for Kubernetes?

    • Answer: Security best practices include using RBAC, network policies, pod security policies (or their replacements), regularly patching nodes and components, and using secrets management tools.

34. How do you troubleshoot a Pod that is stuck in the "Pending" state?

    • Answer: Check for insufficient resources, image pull issues, misconfigured deployments, or problems with the node the Pod is scheduled to run on. Examine the events related to the Pod using `kubectl describe pod`.

35. What are the benefits of using Kubernetes?

    • Answer: Benefits include automated deployment and scaling, self-healing capabilities, improved resource utilization, and increased availability and reliability.

36. What are some challenges of using Kubernetes?

    • Answer: Challenges include the complexity of the system, the need for specialized skills, potential security vulnerabilities, and the learning curve associated with mastering the platform.

37. Describe your experience with Kubernetes (if any).

    • Answer: [This answer should be tailored to your experience. Be specific about any projects you've worked on, tasks you've completed, and tools you've used. If you have no experience, honestly state that and express your enthusiasm for learning.]

38. What are your preferred methods for learning new technologies?

    • Answer: [Describe your learning style - hands-on, documentation, online courses, etc.]

39. How do you handle stressful situations or tight deadlines?

    • Answer: [Describe your approach to stress management and problem-solving under pressure.]

40. Why are you interested in this Kubernetes internship?

    • Answer: [Explain your interest in Kubernetes and the specific reasons you want this internship. Mention relevant skills and aspirations.]

41. What are your salary expectations?

    • Answer: [Research the average salary for similar internships in your location and provide a realistic range.]

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