1. What is Kubernetes?
Kubernetes is an open-source container orchestration platform used to automate deployment, scaling, and management of containerized applications. It helps manage clusters of machines and ensures applications run reliably at scale.
2. What problems does Kubernetes solve?
Kubernetes solves issues like container scheduling, service discovery, load balancing, self-healing, and scaling.
It removes the need for manual container management in production environments.
3. What is a Kubernetes cluster?
A Kubernetes cluster is a set of worker machines (nodes) managed by a control plane. The control plane makes global decisions, while nodes run the actual workloads.
4. What are the main components of Kubernetes architecture?
The main components are the Control Plane and Worker Nodes. Control plane components include kube-apiserver, etcd, scheduler, and controller manager.
5. What is a node in Kubernetes?
A node is a worker machine (VM or physical server) that runs containerized applications. Each node contains kubelet, kube-proxy, and a container runtime.
6. What is a pod?
A pod is the smallest deployable unit in Kubernetes and can contain one or more containers. Containers in a pod share networking, storage, and lifecycle.
7. Why are pods ephemeral?
Pods are designed to be disposable and easily replaceable. If a pod fails, Kubernetes creates a new one instead of repairing the old one.
8. What is a deployment?
A Deployment provides declarative updates for pods and ReplicaSets. It ensures the desired number of replicas are running and handles rolling updates.
9. What is a ReplicaSet?
A ReplicaSet ensures that a specified number of pod replicas are running at any time. Deployments use ReplicaSets internally to manage scaling and updates.
10. What is a StatefulSet?
StatefulSet is used for stateful applications like databases. It provides stable pod identities, persistent storage, and ordered deployment.
11. What is a DaemonSet?
A DaemonSet ensures that a copy of a pod runs on all or specific nodes. It’s commonly used for logging, monitoring, and security agents.
12. What is a Service in Kubernetes?
A Service exposes a set of pods as a stable network endpoint. It enables communication between pods without needing to know their IP addresses.
13. Types of Kubernetes Services?
Common types include ClusterIP, NodePort, LoadBalancer, and ExternalName. Each type serves different networking and exposure needs.
14. What is ClusterIP?
ClusterIP exposes the service only within the Kubernetes cluster. It’s the default service type and used for internal communication.
15. What is NodePort?
NodePort exposes the service on a static port on each node’s IP. It allows external traffic but is not recommended for production at scale.
16. What is a LoadBalancer service?
LoadBalancer provisions an external load balancer (cloud-provider dependent). It routes external traffic directly to Kubernetes services.
17. What is Ingress?
Ingress manages external HTTP and HTTPS access to services. It provides routing, SSL termination, and virtual hosting.
18. What is an Ingress Controller?
An Ingress Controller implements Ingress rules. Examples include NGINX, Traefik, and HAProxy.
19. What is etcd?
etcd is a distributed key-value store used by Kubernetes to store cluster state. It is critical for cluster consistency and reliability.
20. What is kube-apiserver?
kube-apiserver is the entry point for all Kubernetes operations. It validates and processes REST API requests.
21. What is kube-scheduler?
The scheduler assigns pods to suitable nodes based on resource requirements. It considers CPU, memory, affinity rules, and constraints.
22. What is kubelet?
kubelet runs on each node and communicates with the control plane. It ensures containers are running as specified in pod definitions.
23. What is kube-proxy?
kube-proxy manages network rules on nodes. It enables service-to-pod communication using iptables or IPVS.
24. What is a namespace?
Namespaces provide logical isolation within a cluster. They are useful for multi-team environments and resource separation.
25. What are labels and selectors?
Labels are key-value pairs attached to Kubernetes objects. Selectors are used to identify and group resources based on labels.
26. What are annotations?
Annotations store non-identifying metadata on objects. They are commonly used for tooling, monitoring, or documentation.
27. What is a ConfigMap?
ConfigMap stores configuration data separately from application code. It allows configuration changes without rebuilding container images.
28. What is a Secret?
Secrets store sensitive information like passwords or tokens. They are base64-encoded and can be mounted as files or environment variables.
29. How does Kubernetes handle scaling?
Kubernetes supports manual and automatic scaling. Horizontal Pod Autoscaler scales pods based on CPU or custom metrics.
30. What is HPA?
HPA automatically adjusts the number of pod replicas. It uses metrics from Metrics Server or custom monitoring tools.
31. What is a readiness probe?
Readiness probes determine if a pod is ready to receive traffic. If it fails, traffic is removed without restarting the pod.
32. What is a liveness probe?
Liveness probes check if a container is still running properly. If it fails, Kubernetes restarts the container.
33. What is a startup probe?
Startup probes verify if an application has started successfully. They prevent premature liveness probe failures.
34. What is a PersistentVolume (PV)?
A PV is a piece of storage provisioned in the cluster. It exists independently of pod lifecycle.
35. What is a PersistentVolumeClaim (PVC)?
A PVC is a request for storage by a user or pod. It binds to a suitable PersistentVolume.
36. What is StorageClass?
StorageClass defines how storage is dynamically provisioned. It allows automation of volume creation.
37. What is Helm?
Helm is a package manager for Kubernetes. It simplifies deployment using reusable charts.
38. What is a Helm chart?
A Helm chart is a collection of Kubernetes manifests. It defines resources, values, and templates.
39. What is RBAC?
RBAC controls access to Kubernetes resources. It defines who can perform what actions in the cluster.
40. What are Roles and RoleBindings?
Roles define permissions within a namespace. RoleBindings assign those permissions to users or service accounts.
41. What is a ServiceAccount?
A ServiceAccount provides an identity for pods. It’s commonly used for API access from applications.
42. What is network policy?
NetworkPolicy controls traffic between pods. It enhances security by restricting communication.
43. What is CNI?
CNI (Container Network Interface) handles pod networking. Popular CNIs include Calico, Flannel, and Cilium.
44. What is rolling update?
Rolling updates deploy new versions gradually. They minimize downtime by updating pods incrementally.
45. What is blue-green deployment?
Blue-green deployment runs two environments simultaneously. Traffic switches instantly from old to new version.
46. What is canary deployment?
Canary deployment releases changes to a small subset of users. It reduces risk by validating new versions before full rollout.
47. How do you monitor Kubernetes?
Monitoring is done using tools like Prometheus and Grafana. They collect metrics, alerts, and visualize cluster health.
48. How do you troubleshoot a failing pod?
Check pod status, events, and logs using kubectl. Describe and logs commands are key troubleshooting tools.
49. What happens when a node fails?
Kubernetes detects node failure via heartbeats. Pods are rescheduled to healthy nodes automatically.
50. Why is Kubernetes important for DevOps?
Kubernetes enables automation, scalability, and resilience. It aligns perfectly with DevOps principles of CI/CD and infrastructure as code.
Conclusion.
Kubernetes is a core skill for every DevOps engineer, and interview questions often test both conceptual knowledge and real-world experience. By understanding these questions and practicing the answers, you’ll be better prepared to handle Kubernetes interviews with confidence.
- For more information about Kubernetes, visit Jeevi’s page to explore detailed guides and resources.
