Kubernetes Important interview Q&A

Introduction

Kubernetes, often abbreviated as K8s, has become the cornerstone of modern containerized application development and deployment. It’s a powerful tool that enables developers and operations teams to manage containerized applications seamlessly. In this guide, we’ll explore common interview questions about Kubernetes and provide comprehensive answers to help you ace your Kubernetes-related interviews.

1. What is Kubernetes and why is it important?
Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. It is important because it simplifies the management of containers, ensures high availability, scalability, and facilitates rolling updates, making it easier to maintain and scale applications in a dynamic and cloud-native environment.

2. What is the difference between Docker Swarm and Kubernetes?
Docker Swarm is a native clustering and orchestration tool for Docker, while Kubernetes is a more comprehensive, open-source container orchestration platform that can manage containers created with Docker and other container runtimes. Kubernetes offers more advanced features like automatic load balancing, rolling updates, and better scalability.

3. How does Kubernetes handle network communication between containers?
Kubernetes manages network communication through a virtual network called the “Pod Network.” Containers within the same Pod can communicate via localhost, while containers in different Pods use the Kubernetes Service abstraction or DNS for service discovery.

4. How does Kubernetes handle scaling of applications?
Kubernetes handles scaling through various mechanisms like Horizontal Pod Autoscaling (HPA), which automatically adjusts the number of Pods based on resource utilization or custom metrics. It also supports manual scaling via the `kubectl` command or declaratively in YAML files.

5. What is a Kubernetes Deployment and how does it differ from a ReplicaSet?
A Kubernetes Deployment is a higher-level abstraction that manages ReplicaSets. Deployments allow you to declaratively define desired state, handle rolling updates, and provide features like rollbacks. ReplicaSets ensure a specified number of Pod replicas are running.

6. Can you explain the concept of rolling updates in Kubernetes?
Rolling updates in Kubernetes involve gradually replacing old Pods with new ones to ensure zero downtime during updates. It’s achieved by creating new Pods with the updated application version and then gradually scaling down the old Pods.

7. How does Kubernetes handle network security and access control?
Kubernetes provides Network Policies to control traffic between Pods and Role-Based Access Control (RBAC) to manage user and system access to cluster resources. It also supports other security features like Pod Security Policies and Secrets management.

8. Can you give an example of how Kubernetes can be used to deploy a highly available application?
To deploy a highly available application, you would use features like Deployment or StatefulSet to ensure multiple replicas of your application run across different nodes. You’d also use Services for load balancing and possibly Ingress for external access.

9. What is a namespace in Kubernetes? Which namespace does a pod take if we don’t specify any namespace?
A namespace is a virtual cluster within a Kubernetes cluster. If you don’t specify a namespace for a Pod, it will be created in the default namespace.

10. How does Ingress help in Kubernetes?
Ingress is an API object that manages external access to services within a cluster. It enables you to define routing rules, SSL/TLS termination, and load balancing for HTTP and HTTPS traffic to services.

11. Explain different types of services in Kubernetes.
Kubernetes supports several types of services, including ClusterIP, NodePort, LoadBalancer, and ExternalName. Each type serves a different purpose in exposing and accessing services within and outside the cluster.

12. Can you explain the concept of self-healing in Kubernetes and give examples of how it works?
Self-healing in Kubernetes ensures that the desired state of resources is maintained. For example, if a Pod fails, the ReplicationController or Deployment will automatically create a replacement Pod to maintain the desired replica count.

13. How does Kubernetes handle storage management for containers?
Kubernetes provides Persistent Volumes (PVs) and Persistent Volume Claims (PVCs) to manage storage. Containers can request storage resources using PVCs, and Kubernetes ensures that the correct storage is provisioned and attached to Pods.

14. How does the NodePort service work?
NodePort exposes a service on a static port on each node’s IP. When traffic hits this port, it is forwarded to the appropriate service, allowing external access to services.

15. What is a multi-node cluster and single-node cluster in Kubernetes?
A multi-node cluster consists of multiple worker nodes, while a single-node cluster has only one node. Multi-node clusters are typically used in production environments for high availability, while single-node clusters are useful for development and testing.

16. Difference between ‘create’ and ‘apply’ in Kubernetes?
‘Create’ is used to create a new resource, and if it already exists, it will return an error. ‘Apply’ is used to create or update a resource, updating it if it already exists or creating it if it doesn’t. ‘Apply’ is often used for declarative configuration management.

In this blog, we explored key aspects of Kubernetes, answering crucial questions about its importance, networking, scaling, security, and more. The author, Mudit Mathur, welcomes feedback and further discussions on LinkedIn. #Kubernetes #DevOps #ContainerOrchestration #day37 #90daysofdevops