Top 20 Kubernetes Interview Questions and Answers

Kubernetes, originally developed by Google, and maintained by the Cloud Native Computing Foundation (CNCF) is an open-source platform to maintain containerised workloads and services. Kubernetes maintains and automates the deployment, scaling and operation of applications that are contained as containers. This is a powerful bundle of solutions equipping operations engineers to scale and service server setups. Kubernetes orchestrate a large number of containers, ensuring efficiency in their operations, scaling them up and down as required, handling failover and recovering automatically, enabling the well-organised development and deployment of complex applications.

Here are top 20 Kubernetes Interview Questions and Answers:

1. What is Kubernetes?
   Kubernetes, originally developed by Google, and maintained by the Cloud Native Computing Foundation (CNCF) is an open-source platform to maintain containerised workloads and services. Kubernetes maintains and automates the deployment, scaling and operation of applications that are contained as containers. This is a powerful bundle of solutions equipping operations engineers to scale and service server setups. Kubernetes orchestrate a large number of containers, ensuring efficiency in their operations, scaling them up and down as required, handling failover and recovering automatically, enabling the well-organised development and deployment of complex applications.
2. What are K8s?
   This is another term used to refer to Kubernetes.
3. How are Kubernetes and Docker related?
   While both of them are used to manage and deploy containers, Kubernetes and Docker have different purposes in the containers ecosystem. This is one of the most asked Kuberbetes interview questions and answers. Dockers enable developers to build, package and distribute applications as containers. Dockers provide a way to manage these containers to deploy applications in different environments. Kubernetes orchestrates multiple containers across multiple hosts for more efficient use of resources and scaling of applications. Kubernetes can be used to manage containers created using docker and other technologies.
4. What are the features of Kubernetes?
   It is an important question in an interview of Kubernetes question and answers, and these are the features of Kubernetes:
   • In-built service discovery and load-balancing mechanism for distribution of traffic across containers.
   • Kubernetes automates the deployment, scaling and management of of containerised applications.
   • Kubernetes automatically scale the number of containers running based on application demand.
   • Kubernetes securely inject codes and passwords into containers, providing a way for secret management.
   • Kubernetes has many in-built integrations in cloud platforms, to manage applications on different cloud providers.
5. Name the main components of Kubernetes architecture.
   The two primary components of Kubernetes architecture are the master node and the worker node.
6. How does a master node work in Kubernetes?
   The master node manages and controls the set of worker nodes, resembling a cluster in Kubernetes. The nodes manage the clusters and use API to configure and manage the resources within the collection.
7. What is a node in Kubernetes?
   Nodes are responsible for running the containerised workloads which will provide the necessary computing resources of memory, to run the applications. Each node requires a container runtime, to manage the containers of the node, and these nodes are responsible to provide computing resources for containerised applications and are managed by the Kubernetes control plane to ensure that the cluster is maintained adequately.
8. What does the node status contain?
   In this Kubernetes interview question, you need to mention that the node status contains essential components such as address, condition, capacity and info.
9. What is a pod in Kubernetes?
   In Kubernetes, a pod is the smallest and the simplest unit in the object model that represents a single instance of a running process in the cluster, encapsulating one or more clusters, and with the unique IP address attached to the cluster, all containers in the pod share same network namespace, allowing them to communicate at the same interface.
10. What is the job of a kube-scheduler?
    For this Kubernetes interview question, you need to answer how the newly assigned pods are assigned nodes by a kube-scheduler.
11. What are daemon sets?
    A daemon set is a set of pods run only once on a hosting platform, used for host layer attributes like network or monitoring for network, and that can be run on the host only once.
12. What is minikube?
    Minikube allows running a Kubernetes cluster locally on your device and is designed to be lightweight and test the applications locally before using it in a productive environment. Minikube runs a single-node Kubernetes cluster providing a way to experiment with Kubernetes features without a full-scale production cluster.
13. What is a namespace in Kubernetes?
    In this Kubernetes interview question, you need to answer that namespaces divide cluster resources between multiple users, and are meant for environments where many users are spread across different projects and provide an extensive scope of resources.
14. What is ETCD?
    ETCD is an open-source distributed key-value store that provides a reliable and consistent way to store and manage data across a cluster of nodes. It was developed by CoreOS and is now part of the Cloud Native Computing Foundation (CNCF). In this Kubernetes interview question, you need to explain that etcd is designed to be a distributed, highly available, and fault-tolerant system, making it a good choice for storing configuration data and metadata for distributed systems, including Kubernetes. It uses the Raft consensus algorithm to ensure that data is replicated and consistent across all nodes in the cluster, even in the event of failures or network partitions.
15. What is ClusterIP?
    They are a type of service used for internal communication with Kubernetes, providing a stable IP address, to expose the pods to other services in the cluster. Requests sent to this IP address automatically load balanced to the pods behind the service which facilitates scalability and high availability. ClusterIP services are not accessible from outside the cluster. Their main function is used for database services, messaging systems and other services which can be accessed by other applications within the cluster.
16. What is the load balancer in Kubernetes?
    The load balancer service in Kubernetes exposes services to the internet and creates a single IP address forwarding traffic to the service.
17. What are federated clusters?
    This helps to manage Kubernetes clusters as a unified entity. You can deploy, manage and scale applications across multiple clusters that treat them as a single entity. If you have resources in different regions, you can use federated clusters that clustered them together for a global view of the application. By federating clusters, you can ensure that applications are resilient to failures and can quickly recover. This feature helps to scale and manage Kubernetes infrastructure efficiently and for complex environments.
18. What is Kubelect?
    This is a service agent controlling and maintaining a set of pods and runs each node in the cluster and manages the containers running on the node as well as monitors pod specs through the Kubernetes API server. Kubelect is one of the core components of the Kubernetes system, responsible for starting and stopping containers.
19. What is Kube-Proxy?
    Kube-Proxy is a network proxy and load balancer that runs on each node in the cluster. Its primary role is to manage network connectivity between different services and pods within the Kubernetes cluster. For this Kubernetes interview question, you need to mention how Kube-Proxy implements the Kubernetes Service concept, providing a stable and reliable way to have access to a group of pods in a cluster, and by creating a set of network rules on each node in the cluster that allows incoming traffic to be routed to the appropriate service or pod. Kube-Proxy can also perform load balancing between pods, distributing incoming requests evenly across the available instances.
20. How to get a static IP for the Kubernetes load balancer?
    For this Kubernetes interview question, You need to change the DNS records to achieve a static IP for the Kubernetes load balancer, as Kubernetes is capable to assign a new static IP address.