Google Kubernetes Engine Interview Questions and Answers for freshers

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. What is Google Kubernetes Engine (GKE)?

   • Answer: Google Kubernetes Engine (GKE) is a managed Kubernetes service offered by Google Cloud Platform (GCP). It simplifies the deployment and management of Kubernetes clusters, handling tasks like infrastructure provisioning, node management, and upgrades.

3. Explain the concept of containers.

   • Answer: Containers are standardized, executable units of software that package code and all its dependencies (libraries, system tools, settings) into a single unit. This ensures consistent execution across different environments.

4. What is a Pod in Kubernetes?

   • Answer: A Pod is the smallest deployable unit in Kubernetes. It represents a running process and consists of one or more containers sharing resources like storage and networking.

5. 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.

6. What are Services in Kubernetes?

   • Answer: Services provide a stable IP address and DNS name for a set of Pods. They abstract away the underlying Pod IPs, allowing applications to communicate with each other regardless of Pod changes.

7. Explain Kubernetes namespaces.

   • Answer: Namespaces provide a logical way to divide a cluster into multiple virtual clusters. They help organize resources and isolate different teams or applications within the same Kubernetes cluster.

8. What are ConfigMaps and Secrets in Kubernetes?

   • Answer: ConfigMaps store configuration data for applications, while Secrets store sensitive information like passwords and API keys. Both are externalized configurations to keep application code clean and secure.

9. What are Persistent Volumes (PVs) and Persistent Volume Claims (PVCs)?

   • Answer: PVs represent storage resources provisioned by an administrator, while PVCs are requests from applications for storage. They decouple storage from applications, allowing for flexibility and portability.

10. Explain the concept of Kubernetes nodes.

    • Answer: Nodes are the physical or virtual machines that make up a Kubernetes cluster. They run the kubelet, which communicates with the master components to manage Pods.

11. What is a Kubernetes master node?

    • Answer: The master node (or control plane) is responsible for managing the entire cluster, including scheduling Pods, managing nodes, and providing an API for interacting with the cluster.

12. What is the kubelet?

    • Answer: The kubelet is an agent that runs on each node in the cluster. It communicates with the master node to receive instructions and manage Pods running on that node.

13. What is kubectl?

    • Answer: Kubectl is the command-line interface (CLI) for interacting with a Kubernetes cluster. It allows you to manage and inspect resources within the cluster.

14. How do you create a Kubernetes Deployment using kubectl?

    • Answer: You create a Deployment by applying a YAML file defining the Deployment specification using the command `kubectl apply -f deployment.yaml`.

15. How do you scale a Deployment in Kubernetes?

    • Answer: You can scale a Deployment using `kubectl scale deployment --replicas=`.

16. What are different types of Kubernetes Services?

    • Answer: Common types include ClusterIP (internal), NodePort (external on node IPs), LoadBalancer (external cloud load balancer), and Ingress (advanced routing).

17. What is an Ingress in Kubernetes?

    • Answer: An Ingress is an API object that manages external access to services in a cluster, typically using a reverse proxy and load balancing.

18. Explain Kubernetes labels and selectors.

    • Answer: Labels are key-value pairs attached to Kubernetes objects for organization and selection. Selectors are used to identify objects based on their labels.

19. What are Kubernetes annotations?

    • Answer: Annotations are similar to labels, but they are intended for metadata that is not used by the Kubernetes core, often used for external tooling or information.

20. What are the different types of Kubernetes resource requests and limits?

    • Answer: Resources like CPU and memory can be specified as requests (minimum guaranteed) and limits (maximum allowed) for each container. This ensures resource allocation and prevents resource starvation.

21. What is a StatefulSet in Kubernetes?

    • Answer: A StatefulSet manages stateful applications that require persistent storage and stable network identities. It ensures that Pods are recreated with the same name and persistent storage.

22. What is a DaemonSet in Kubernetes?

    • Answer: A DaemonSet ensures that a single instance of a Pod is running on every node in the cluster. Often used for system daemons or agents.

23. What is a Job in Kubernetes?

    • Answer: A Job runs a finite task to completion. It creates one or more Pods, and once they complete successfully, the Job is considered finished.

24. What is a CronJob in Kubernetes?

    • Answer: A CronJob schedules Jobs to run periodically based on a cron expression, similar to Unix cron.

25. What is a PodDisruptionBudget (PDB)?

    • Answer: A PDB limits the number of Pods in a Deployment that can be unavailable during a disruption, such as a node upgrade or maintenance.

26. Explain the concept of Kubernetes rolling updates.

    • Answer: Rolling updates gradually replace old Pods with new ones, minimizing downtime and ensuring high availability during updates.

27. What are some common Kubernetes monitoring tools?

    • Answer: Prometheus, Grafana, Datadog, and others are commonly used for monitoring Kubernetes clusters and applications.

28. What is a NetworkPolicy in Kubernetes?

    • Answer: NetworkPolicies define network access control for Pods, allowing you to control traffic flow within the cluster for enhanced security.

29. What is a ResourceQuota in Kubernetes?

    • Answer: ResourceQuotas enforce limits on resource consumption (CPU, memory, etc.) within a namespace, preventing resource exhaustion.

30. Explain the concept of Kubernetes auto-scaling.

    • Answer: Auto-scaling automatically adjusts the number of Pods in a Deployment based on resource utilization or other metrics, ensuring optimal resource usage.

31. What are some advantages of using GKE?

    • Answer: Advantages include managed infrastructure, automatic upgrades, high availability, scalability, and integration with other GCP services.

32. What are the different node pools in GKE?

    • Answer: GKE supports multiple node pools with different machine types and configurations allowing for specialized workloads.

33. How do you manage nodes in GKE?

    • Answer: Nodes are managed through the Google Cloud Console or the `gcloud` command-line tool.

34. What are GKE Autopilot and its benefits?

    • Answer: GKE Autopilot is a fully managed node pool. Benefits include simplified node management, automatic scaling, and reduced operational overhead.

35. What are GKE node pools?

    • Answer: Node pools are groups of nodes with the same configuration (machine type, OS, etc.). They provide flexibility for managing different types of workloads.

36. How do you upgrade a GKE cluster?

    • Answer: GKE clusters can be upgraded using the Google Cloud Console or the `gcloud` command-line tool, with options for different upgrade strategies.

37. How do you create a GKE cluster?

    • Answer: GKE clusters are created using the Google Cloud Console, the `gcloud` command-line tool, or the Kubernetes API.

38. What are the different authentication methods for GKE?

    • Answer: GKE supports various authentication methods, including Google Cloud service accounts, kubeconfig files, and others.

39. Explain GKE's integration with other GCP services.

    • Answer: GKE integrates seamlessly with other GCP services such as Cloud SQL, Cloud Storage, and Cloud Logging for enhanced functionality.

40. What are some best practices for securing a GKE cluster?

    • Answer: Best practices include using IAM roles, Network Policies, Secrets management, regular updates, and vulnerability scanning.

41. How do you troubleshoot common GKE issues?

    • Answer: Troubleshooting involves checking logs, monitoring metrics, examining Pod status, and using kubectl commands to investigate issues.

42. What is the role of the kube-proxy in GKE?

    • Answer: The kube-proxy is a network proxy that runs on each node and implements the Kubernetes Service concept, enabling service discovery and load balancing.

43. What is the difference between a Kubernetes cluster and a GKE cluster?

    • Answer: A Kubernetes cluster is a general concept, while a GKE cluster is a specific implementation of Kubernetes managed by Google Cloud Platform.

44. How does GKE handle high availability?

    • Answer: GKE provides high availability through features like multiple master nodes, redundant components, and automated failover mechanisms.

45. What is the concept of zones and regions in GKE?

    • Answer: Zones are physical locations within a region where GKE nodes can be deployed, offering geographical redundancy and fault tolerance.

46. How does GKE handle node failures?

    • Answer: GKE automatically detects and handles node failures by rescheduling Pods to healthy nodes, ensuring application availability.

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

    • Answer: Readiness probes check if a container is ready to accept traffic. Liveness probes check if a container is still running correctly and should be restarted if not.

48. What are some common GKE pricing models?

    • Answer: GKE pricing is based on various factors including node usage, storage, and other resources consumed.

49. How do you monitor the performance of your GKE cluster?

    • Answer: Use tools like the Google Cloud Monitoring console, integrated metrics dashboards, and logging to monitor cluster performance.

50. What are some best practices for cost optimization in GKE?

    • Answer: Optimize node sizing, leverage spot instances (preemptible nodes), right-size deployments, utilize autoscaling, and monitor resource utilization.

51. How do you back up and restore a GKE cluster?

    • Answer: Strategies include using third-party tools or custom scripts to back up etcd (the Kubernetes database) and application data, then restoring from backups.

52. What are some security considerations when using GKE?

    • Answer: Security concerns include securing the master nodes, managing Kubernetes secrets, implementing network policies, and securing application code.

53. How do you manage secrets securely in GKE?

    • Answer: Use Kubernetes Secrets and consider leveraging Google Cloud Secret Manager for enhanced security and integration with other GCP services.

54. What is the role of the etcd database in GKE?

    • Answer: Etcd is the key-value store that stores the Kubernetes cluster state, including configurations, pods, and other resources.

55. Explain the concept of horizontal pod autoscaling (HPA) in GKE.

    • Answer: HPA automatically scales the number of Pods in a Deployment based on CPU utilization or other metrics, ensuring efficient resource usage and responsiveness.

56. What are the different authentication options for accessing your GKE cluster?

    • Answer: Options include using Google Cloud service accounts, setting up a kubeconfig file with appropriate credentials, and using other authentication providers.

57. How can you integrate your GKE cluster with other cloud services?

    • Answer: GKE offers seamless integration with various Google Cloud services like Cloud Storage, Cloud SQL, Cloud Pub/Sub, and more through well-defined APIs and tools.

58. What are some common challenges encountered when deploying applications to GKE?

    • Answer: Challenges may include network configuration, resource allocation, security policies, debugging, and managing complex deployments.

59. How can you troubleshoot networking issues in your GKE cluster?

    • Answer: Troubleshooting networking involves checking NetworkPolicies, inspecting Pod status, examining logs, and analyzing network connectivity using various tools.

60. What are the different logging options available for GKE?

    • Answer: Options include using the Google Cloud Logging service, integrating with third-party logging solutions, and collecting logs from application containers.

61. How can you improve the security posture of your GKE cluster?

    • Answer: Enhance security through network policies, regularly updated cluster images, strong authentication mechanisms, and monitoring security logs.

62. What is the difference between a managed and an unmanaged Kubernetes cluster?

    • Answer: Managed Kubernetes clusters (like GKE) handle infrastructure maintenance, while unmanaged clusters require manual infrastructure and cluster management.

63. What are some considerations for choosing a node pool configuration for your GKE cluster?

    • Answer: Considerations include application resource requirements, cost constraints, desired scalability, and specific hardware needs (like GPUs).

64. How do you handle application updates in GKE with minimal downtime?

    • Answer: Use Deployment's rolling updates, canary deployments, or blue-green deployments to minimize downtime during application updates.

65. What are some common metrics to monitor in your GKE cluster?

    • Answer: Essential metrics include CPU utilization, memory usage, network traffic, disk I/O, pod restarts, and application-specific metrics.

66. What are the different ways to access your GKE cluster?

    • Answer: Access includes using the Google Cloud Console, kubectl command-line tool, and various APIs.

67. How can you troubleshoot Pod failures in your GKE cluster?

    • Answer: Troubleshooting includes checking Pod logs, examining events, verifying resource limits, and inspecting the Pod's status and conditions.

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