Top 50 Kubernetes Interview Questions and Answers for 2024

Kubernetes has emerged as the de facto standard for container orchestration, enabling organizations to efficiently deploy, scale, and manage containerized applications. Whether you’re a seasoned Kubernetes pro or just starting your journey with containerization, mastering Kubernetes is essential for success in today’s cloud-native landscape. In this blog post, we’ll delve into 50 key Kubernetes interview questions along with comprehensive answers to help you prepare for your next Kubernetes interview.

1. What is Kubernetes?

Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.

What are the key components of Kubernetes architecture? Key components include Master Node (kube-apiserver, kube-scheduler, kube-controller-manager, etcd), Worker Node (kubelet, kube-proxy, Container runtime), and Add-ons (DNS, Dashboard, Ingress Controller, etc.).

2. Explain Pods in Kubernetes.

A pod is the smallest deployable unit in Kubernetes, consisting of one or more containers that share storage and network resources. Pods represent a single instance of a running process in Kubernetes.

3. How do you scale applications in Kubernetes?

Applications can be scaled horizontally or vertically in Kubernetes. Horizontal scaling is achieved by increasing the number of pod replicas, while vertical scaling involves modifying the CPU or memory resources allocated to individual pods.

4. What is a Kubernetes Deployment?

A Deployment in Kubernetes provides declarative updates to applications. It manages the deployment and scaling of a set of pods, ensuring that the desired state is maintained.

5. Explain Kubernetes Service.

A Kubernetes Service is an abstraction that defines a logical set of pods and a policy by which to access them. It provides a stable endpoint for accessing the pods, regardless of changes in the underlying infrastructure.

6. What is a Kubernetes Namespace?

A Namespace in Kubernetes is a way to divide cluster resources between multiple users (or projects/teams). It provides a scope for names, allowing multiple users to share the same cluster without interfering with each other.

7. How do you troubleshoot Kubernetes cluster issues?

Troubleshooting in Kubernetes involves examining logs, checking resource utilization, verifying configurations, and using debugging tools like kubectl describe and kubectl logs.

8. What is a Kubernetes ConfigMap?

A ConfigMap in Kubernetes is an API object used to store non-confidential data in key-value pairs. It allows decoupling configuration from pod definitions, making it easier to manage and update configurations.

9. Explain Kubernetes Secret.

Kubernetes Secret is an object that stores sensitive data such as passwords, OAuth tokens, and SSH keys. It ensures that this information is stored securely and made available only to authorized users and applications.

10. What is Kubernetes Ingress?

Kubernetes Ingress is an API object that manages external access to services within a Kubernetes cluster. It provides HTTP and HTTPS routing, load balancing, and SSL termination.

11. What is a Kubernetes StatefulSet?

StatefulSet is a Kubernetes API object used for managing stateful applications. It provides guarantees about the ordering and uniqueness of pod deployment, stable network identities, and persistent storage.

12. Explain Kubernetes DaemonSet.

DaemonSet in Kubernetes ensures that all (or some) nodes run a copy of a specific pod. It is useful for deploying system daemons such as log collectors, monitoring agents, or network storage daemons on every node.

13. How do you manage storage in Kubernetes?

Kubernetes provides various options for managing storage, including PersistentVolumes (PVs), PersistentVolumeClaims (PVCs), Storage Classes, StatefulSets, and Volume Plugins (CSI).

14. What is Kubernetes Horizontal Pod Autoscaler (HPA)?

Horizontal Pod Autoscaler automatically scales the number of pods in a replication controller, deployment, or replica set based on observed CPU utilization (or custom metrics) to maintain optimal performance.

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

RBAC in Kubernetes is a method for controlling access to resources based on the roles assigned to users or service accounts. It allows fine-grained control over who can access what resources within the cluster.

16. What is Kubernetes Helm?

Helm is a package manager for Kubernetes that simplifies the process of deploying, managing, and upgrading applications on Kubernetes clusters. It uses charts (packaged applications) to define the structure of an application.

17. What is Kubernetes Operator?

Kubernetes Operator is a method of packaging, deploying, and managing a Kubernetes application. It extends Kubernetes API to create, configure, and manage complex stateful applications on behalf of users.

18. Explain Kubernetes Network Policies.

Network Policies in Kubernetes define rules for how groups of pods can communicate with each other and other network endpoints. They provide network segmentation and isolation within the cluster.

19. What is the difference between a StatefulSet and a Deployment in Kubernetes?

StatefulSet is suitable for managing stateful applications that require stable network identities and persistent storage, while Deployment is ideal for stateless applications that can be scaled horizontally.

20. How does Kubernetes handle application updates and rollbacks?

Kubernetes supports rolling updates and rollbacks through declarative configurations. It gradually replaces old pods with new ones during updates and allows reverting to previous configurations in case of issues.

21. What is the role of etcd in Kubernetes?

etcd is a distributed key-value store used by Kubernetes to store cluster data, including configuration settings, state information, and metadata. It provides high availability and consistency for cluster management.

22. Explain Kubernetes Admission Controllers.

Admission Controllers in Kubernetes are plugins that intercept and modify requests to the API server. They enforce security policies, mutate incoming requests, and validate resource configurations before they are persisted.

23. What are Kubernetes Labels and Selectors?

Labels are key-value pairs attached to objects in Kubernetes, while Selectors are used to identify objects based on their labels. They enable grouping, filtering, and selecting resources for various purposes such as querying or applying policies.

24. How does Kubernetes manage container networking?

Kubernetes manages container networking through its networking model, which typically involves assigning each pod an IP address, creating a virtual network interface for each container, and configuring networking rules using CNI plugins.

25. What is the Kubernetes Control Plane?

The Kubernetes Control Plane is a collection of processes that control the state of the cluster, including scheduling, scaling, and managing workloads. It consists of the kube-apiserver, kube-scheduler, kube-controller-manager, and etcd.

26. Explain Kubernetes CronJobs.

CronJobs in Kubernetes are used to run jobs on a periodic schedule, similar to cron jobs in Unix-like operating systems. They allow users to automate recurring tasks such as backups, batch jobs, or maintenance tasks.

27. How do you monitor Kubernetes clusters?

Kubernetes clusters can be monitored using various tools such as Prometheus, Grafana, Kubernetes Dashboard, Kube-state-metrics, and custom monitoring solutions. These tools provide insights into cluster health, resource usage, and application performance.

28. What is Kubernetes Pod Affinity and Anti-Affinity?

Pod Affinity and Anti-Affinity are mechanisms in Kubernetes for influencing pod scheduling decisions. Affinity ensures that pods are scheduled close to or far from certain pods, nodes, or node labels, while Anti-Affinity prevents co-location of pods.

29. Explain Kubernetes Custom Resources.

Custom Resources in Kubernetes allow users to extend the Kubernetes API with their own API objects and controllers. They enable the creation of custom resources tailored to specific use cases or applications

30. How does Kubernetes manage container networking?

Kubernetes manages container networking through its networking model, which typically involves assigning each pod an IP address, creating a virtual network interface for each container, and configuring networking rules using CNI plugins.

31. Explain Kubernetes HorizontalPodAutoscaler (HPA).

HorizontalPodAutoscaler (HPA) automatically adjusts the number of replicas in a Deployment, ReplicaSet, or ReplicationController based on observed CPU utilization or custom metrics, ensuring optimal resource allocation.

32. What is a Kubernetes Job?

Kubernetes Job is an API object used to run pods in a one-off manner until successful completion. It is suitable for batch processing, ETL jobs, or any task that needs to run to completion.

33. Explain Kubernetes StatefulSet and its use cases.

StatefulSet is a Kubernetes controller that manages stateful applications, providing stable, persistent storage and unique network identities. It is used for databases, key-value stores, and other stateful workloads.

34. How do you upgrade Kubernetes clusters?

Kubernetes clusters can be upgraded using tools like kubeadm, kops, or by leveraging managed Kubernetes services. The process involves updating the control plane components and then upgrading worker nodes.

35. What is the difference between a ConfigMap and a Secret in Kubernetes?

ConfigMap stores non-sensitive configuration data in key-value pairs, while Secret stores sensitive information like passwords or API tokens. Both are used to decouple configuration from pod definitions.

36. Explain Kubernetes liveness and readiness probes.

Liveness probes are used to determine if a container is running properly, restarting it if necessary. Readiness probes indicate whether a container is ready to serve traffic, enabling or disabling it in the service load balancer.

37. What is the purpose of Kubernetes Role and RoleBinding?

Kubernetes Role defines a set of permissions (verbs) within a namespace, while RoleBinding binds a Role to a user, group, or service account, granting access to specific resources.

38. How do you perform rolling updates in Kubernetes?

Rolling updates in Kubernetes involve gradually replacing old pods with new ones to minimize downtime and maintain application availability. This is typically done by updating the Deployment configuration.

39. Explain the difference between a ReplicaSet and a ReplicationController.

ReplicaSet is the successor to ReplicationController, providing more advanced selectors and scaling options. While ReplicationController can only scale based on the number of replicas, ReplicaSet allows more complex selectors and updates.

40. What are Kubernetes Persistent Volumes (PV) and Persistent Volume Claims (PVC)?

Persistent Volumes (PVs) are storage resources provisioned by the cluster administrator, while Persistent Volume Claims (PVCs) are requests made by users for storage resources. PVCs consume PVs and provide a way for applications to use storage.

41. Explain Kubernetes Admission Controllers and give examples.

Admission Controllers intercept and modify requests to the Kubernetes API server, enforcing policies and validating resource configurations before they are persisted. Examples include PodSecurityPolicy, MutatingAdmissionWebhook, and ValidatingAdmissionWebhook.

42. What is Kubernetes Pod Security Policy (PSP)?

Pod Security Policy is a cluster-level resource that controls security-sensitive aspects of the pod specification. It defines conditions that pods must meet to be accepted into the system, ensuring a secure runtime environment.

43. Explain Kubernetes Resource Quotas and Limit Ranges.

Resource Quotas limit the aggregate resource consumption (CPU, memory, storage) across all pods in a namespace, while Limit Ranges set default resource requests and limits for containers within pods.

44. How does Kubernetes handle service discovery and load balancing?

Kubernetes Service provides a stable endpoint for accessing pods, while kube-proxy handles service discovery and load balancing by routing traffic to the appropriate pod endpoints using iptables or IPVS.

45. What is Kubernetes Pod Priority and Preemption?

Pod Priority and Preemption are mechanisms in Kubernetes for scheduling pods based on priority levels. Pods with higher priority get scheduled first, and lower priority pods can be evicted to make room for higher priority ones.

46. What are Kubernetes Taints and Tolerations?

Taints and Tolerations are mechanisms in Kubernetes for controlling pod placement. Taints are applied to nodes, repelling certain pods, while Tolerations allow pods to tolerate nodes with specific taints.

47. Explain Kubernetes Horizontal Pod Autoscaler (HPA) metrics.

HPA can scale pods based on CPU utilization, custom metrics, or a combination of both. Custom metrics allow autoscaling based on application-specific metrics like queue length or response time.

48. How does Kubernetes handle rolling back deployments?

Kubernetes supports rolling back deployments by reverting to a previous revision of the Deployment configuration. It gradually rolls back to the previous state, ensuring minimal disruption to the application.

49. What is the difference between Kubernetes StatefulSet and DaemonSet?

StatefulSet manages stateful applications with persistent storage and stable network identities, while DaemonSet ensures that a copy of a pod runs on each node in the cluster, typically used for system daemons or logging agents.

50. Explain Kubernetes Cluster Autoscaler.

Cluster Autoscaler automatically adjusts the size of a Kubernetes cluster based on resource utilization and pod scheduling requirements. It scales the underlying infrastructure by adding or removing nodes to meet demand, ensuring optimal resource allocation.