Google Kubernetes Engine 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 components of Kubernetes.

   • Answer: Key components include the control plane (kube-apiserver, scheduler, controller-manager, etcd) and the node components (kubelet, kube-proxy, container runtime). The control plane manages the cluster state, while nodes run the containers.

3. What is a Pod in Kubernetes?

   • Answer: A Pod is the smallest deployable unit in Kubernetes. It represents a running process, typically a single container, but can also include multiple containers that share resources and a network namespace.

4. What are Deployments in Kubernetes?

   • Answer: Deployments manage the desired state of a set of Pods. They provide declarative updates, rolling updates, rollbacks, and manage replicas to ensure the desired number of Pods are always running.

5. What are StatefulSets in Kubernetes?

   • Answer: StatefulSets are used to manage stateful applications where Pods need persistent storage and unique network identities. They ensure that Pods are created and terminated in a specific order and maintain their persistent storage across restarts.

6. Explain Kubernetes Services.

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

7. What are Ingresses in Kubernetes?

   • Answer: Ingresses act as reverse proxies and load balancers for external access to services within the cluster. They route external traffic to different services based on rules defined in the Ingress resource.

8. Describe Kubernetes Namespaces.

   • Answer: Namespaces provide a way to logically partition the cluster into multiple virtual clusters. This allows teams to share a single Kubernetes cluster while isolating their resources and preventing conflicts.

9. What is a Kubernetes Node?

   • Answer: A Node is a worker machine in the cluster that runs Pods. It has the kubelet, kube-proxy, and a container runtime (like Docker or containerd) installed.

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

    • Answer: PVs represent storage units available to the cluster, while PVCs are requests for storage by Pods. PVCs are bound to PVs to provide persistent storage to applications.

11. 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 for secure configuration management.

12. How does Kubernetes handle scaling?

    • Answer: Kubernetes scales applications by automatically creating or deleting Pods based on resource usage or defined replica counts in deployments or statefulsets. Horizontal Pod Autoscaling (HPA) automates scaling based on CPU usage or custom metrics.

13. Explain the Kubernetes scheduler.

    • Answer: The scheduler is a component of the control plane that decides which Node to place a Pod on based on resource availability, constraints, and other factors.

14. What is a Kubernetes ReplicaSet?

    • Answer: A ReplicaSet ensures that a specified number of Pods are running. It's often used as a building block for more complex controllers like Deployments.

15. Describe Kubernetes DaemonSets.

    • Answer: DaemonSets ensure that a single instance of a Pod is running on every Node in the cluster. This is useful for system-level daemons or agents.

16. What are Jobs and CronJobs in Kubernetes?

    • Answer: Jobs run a specific task to completion, while CronJobs schedule Jobs to run periodically based on a cron expression.

17. What is a Pod's lifecycle?

    • Answer: A Pod's lifecycle includes Pending, Running, Succeeded, Failed, and Unknown states. It progresses through these states as it's scheduled, starts, runs, and completes or fails.

18. Explain Kubernetes resource limits and requests.

    • Answer: Resource requests specify the minimum resources a Pod needs, while resource limits specify the maximum resources it can use. This helps with resource allocation and preventing resource contention.

19. How do you troubleshoot a Kubernetes Pod that is not running?

    • Answer: Troubleshooting involves checking the Pod's logs, describing the Pod to see its status and events, examining resource limits and requests, checking Node resources, and inspecting the kubelet logs.

20. What are Kubernetes labels and selectors?

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

21. Explain the concept of Kubernetes annotations.

    • Answer: Annotations are similar to labels but are intended for metadata that is not used by the Kubernetes system itself. They are typically used for external tools or human-readable information.

22. What are the different types of Kubernetes Services?

    • Answer: Common service types include ClusterIP (internal cluster access), NodePort (external access via Node IPs), LoadBalancer (cloud-provider managed load balancer), and ExternalName (maps to an external DNS name).

23. How do you expose a Kubernetes service externally?

    • Answer: You can expose a service externally using NodePort, LoadBalancer, or Ingress depending on your needs and infrastructure.

24. What is kubectl?

    • Answer: Kubectl is the command-line tool for interacting with a Kubernetes cluster. It's used to create, manage, and monitor Kubernetes objects.

25. How do you monitor the health of a Kubernetes cluster?

    • Answer: You can use monitoring tools like Prometheus, Grafana, and the Kubernetes dashboard to monitor the health of nodes, Pods, and other cluster components.

26. What is a Helm chart?

    • Answer: A Helm chart is a package manager for Kubernetes. It allows you to easily deploy and manage complex applications in a Kubernetes cluster.

27. Explain the difference between a Helm chart and a Helm release.

    • Answer: A Helm chart is a template for deploying an application, while a Helm release is an instance of a chart deployed to a Kubernetes cluster.

28. What are some best practices for securing a Kubernetes cluster?

    • Answer: Best practices include using Role-Based Access Control (RBAC), network policies, pod security policies (or their replacements like Pod Security Admission), and regularly updating Kubernetes components.

29. What are NetworkPolicies in Kubernetes?

    • Answer: NetworkPolicies allow you to control network traffic between Pods within a Kubernetes cluster. They provide fine-grained control over network access.

30. Explain the concept of Kubernetes RBAC.

    • Answer: RBAC (Role-Based Access Control) provides granular control over access to Kubernetes resources. It allows you to assign specific permissions to users and groups based on their roles.

31. What is a Kubernetes operator?

    • Answer: A Kubernetes operator is a software extension that uses the Kubernetes API to manage the operational lifecycle of complex stateful applications.

32. What are some common Kubernetes monitoring tools?

    • Answer: Common tools include Prometheus, Grafana, Datadog, and Sysdig.

33. How do you debug a Kubernetes application?

    • Answer: Debugging involves inspecting application logs, using debuggers within containers, checking resource usage, examining metrics, and using tools like `kubectl debug`.

34. Explain the difference between `kubectl apply` and `kubectl create`.

    • Answer: `kubectl apply` uses declarative configuration to manage the desired state, while `kubectl create` creates resources without managing their state.

35. What is a Kubernetes custom resource definition (CRD)?

    • Answer: A CRD allows you to extend the Kubernetes API by defining your own custom resources.

36. What are some best practices for designing Kubernetes deployments?

    • Answer: Best practices include designing for scalability, resilience, security, observability, and using appropriate resource limits and requests.

37. How do you handle secrets in Kubernetes securely?

    • Answer: Use Kubernetes Secrets, avoid hardcoding secrets in application code, leverage tools like HashiCorp Vault or dedicated secret management solutions.

38. What are the benefits of using Google Kubernetes Engine (GKE)?

    • Answer: Benefits include fully managed Kubernetes, integration with other Google Cloud services, autoscaling, security features, and ease of use.

39. How does GKE differ from other Kubernetes offerings?

    • Answer: GKE offers seamless integration with other Google Cloud Platform services, strong security features, and a highly scalable and reliable platform.

40. Explain GKE Autopilot.

    • Answer: GKE Autopilot is a fully managed mode of GKE that automatically handles node management, scaling, and upgrades, simplifying cluster operations.

41. What are GKE node pools?

    • Answer: GKE node pools are groups of nodes with similar configurations within a cluster. They allow for different node types to meet varying application needs.

42. How do you manage GKE cluster upgrades?

    • Answer: GKE handles many upgrades automatically, but you can control the upgrade process through the Google Cloud console or the `gcloud` command-line tool.

43. Explain GKE networking concepts.

    • Answer: GKE uses Virtual Private Cloud (VPC) networking for secure communication between nodes and services. It includes concepts like VPC networking, subnets, and firewalls.

44. How do you monitor GKE clusters?

    • Answer: GKE provides monitoring through Google Cloud Monitoring, offering insights into cluster health, resource usage, and application performance.

45. What are GKE's security features?

    • Answer: GKE's security features include integration with Identity and Access Management (IAM), network policies, encryption at rest and in transit, and security best practices baked into the platform.

46. How do you manage costs in GKE?

    • Answer: Cost management involves right-sizing nodes, using autoscaling effectively, utilizing spot instances, and monitoring resource usage with Google Cloud Billing.

47. What are some common GKE troubleshooting techniques?

    • Answer: Techniques include checking logs, using Cloud Monitoring, inspecting resource usage, reviewing the cluster's events, and leveraging Google Cloud support.

48. How do you back up and restore GKE clusters?

    • Answer: Backup and restoration often involves using tools like Velero or taking snapshots of persistent volumes and then recreating the cluster.

49. Explain GKE's integration with other Google Cloud services.

    • Answer: GKE integrates with services like Cloud SQL, Cloud Storage, Cloud Pub/Sub, Cloud Logging, and many others, simplifying application development and deployment.

50. What are the different GKE pricing models?

    • Answer: Pricing depends on the node type, usage, and features like Autopilot. It's generally based on a per-node, per-hour or per-second model.

51. How do you handle node failures in GKE?

    • Answer: GKE automatically handles node failures by replacing unhealthy nodes and rescheduling Pods on healthy nodes.

52. Explain the concept of GKE node auto-provisioning.

    • Answer: GKE node auto-provisioning dynamically scales the number of nodes in a cluster based on demand, automatically creating or deleting nodes as needed.

53. What are some best practices for deploying applications to GKE?

    • Answer: Best practices include using container images from a registry, utilizing Helm charts for deployment, implementing monitoring and logging, and adhering to security best practices.

54. How do you secure access to your GKE cluster?

    • Answer: Secure access involves using IAM roles and permissions, restricting access to authorized users and services, and utilizing strong authentication methods.

55. Describe how to implement a CI/CD pipeline for GKE.

    • Answer: This typically involves using tools like Jenkins, GitLab CI, or Google Cloud Build to automate the build, test, and deployment process to GKE.

56. What are the different authentication methods for GKE?

    • Answer: GKE supports authentication methods like Google Cloud credentials, service accounts, and kubeconfig files.

57. Explain GKE's support for different container runtimes.

    • Answer: GKE supports various container runtimes, including Docker, containerd, and CRI-O.

58. How do you use GKE's logging and monitoring capabilities?

    • Answer: Use Google Cloud Logging and Monitoring to gather logs and metrics from your applications and the Kubernetes cluster itself.

59. What is the role of `gcloud` in managing GKE?

    • Answer: `gcloud` is the command-line tool for interacting with Google Cloud Platform, including managing GKE clusters, node pools, and other resources.

60. Explain the concept of GKE's regional and zonal clusters.

    • Answer: Regional clusters span multiple zones within a region for high availability, while zonal clusters are limited to a single zone.

61. How do you manage different versions of Kubernetes in GKE?

    • Answer: GKE supports multiple Kubernetes versions. You can create clusters with specific versions and upgrade them as needed.

62. What are some common challenges when using GKE?

    • Answer: Challenges might include understanding the pricing model, managing costs, troubleshooting complex issues, and dealing with networking configurations.

63. How do you scale your applications running on GKE?

    • Answer: Scaling can be done manually or automatically through Horizontal Pod Autoscaling (HPA) based on resource utilization or custom metrics.

64. What are the different types of nodes available in GKE?

    • Answer: GKE offers various node types with different CPU, memory, and storage configurations to meet diverse application requirements.

65. How do you troubleshoot connectivity issues in a GKE cluster?

    • Answer: Troubleshooting involves checking network policies, firewalls, DNS settings, and inspecting the cluster's networking configuration.

66. Explain the concept of GKE node taints and tolerations.

    • Answer: Taints mark nodes with specific properties, and tolerations allow Pods to run on nodes with those taints.

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