Kubernetes Important interview Questions.

What is Kubernetes and why it is important?

Kubernetes is an open-source container orchestration system that helps manage and automate the deployment, scaling, and management of containerized applications. Kubernetes is important because it allows developers to focus on writing code without worrying about the underlying infrastructure. It also provides a standardized way of deploying and managing applications across different environments and cloud providers.

What is difference between docker swarm and kubernetes?

1. Docker Swarm and Kubernetes are both container orchestration systems, but there are some differences between them. Docker Swarm is simpler and easier to use, while Kubernetes is more powerful and flexible. Kubernetes has more features and is more suitable for large and complex deployments, while Docker Swarm is better for small and simple deployments.

How does Kubernetes handle network communication between containers?

1. Kubernetes handles network communication between containers using a networking model called the Container Network Model (CNM). CNM provides a way for containers to communicate with each other using a network overlay. Kubernetes uses a software-defined network (SDN) to manage network traffic between containers.

How does Kubernetes handle scaling of applications?

1. Kubernetes handles scaling of applications using a feature called Horizontal Pod Autoscaling (HPA). HPA automatically scales the number of replicas of a pod based on metrics such as CPU usage or network traffic.

What is a Kubernetes Deployment and how does it differ from a ReplicaSet?

1. A Kubernetes Deployment is a higher-level object that manages ReplicaSets. A ReplicaSet ensures that a specified number of replicas of a pod are running at any given time. A Deployment provides declarative updates for ReplicaSets, such as rolling updates and rollbacks.

Explain the concept of rolling updates in Kubernetes?

1. Rolling updates in Kubernetes allow you to update an application's code or configuration without downtime. Kubernetes performs a rolling update by gradually updating a portion of the pods, while the rest of the pods continue to serve traffic. Once the updated pods are ready, Kubernetes continues the update process until all pods are updated.

How does Kubernetes handle network security and access control?

1. Kubernetes provides network security and access control through features such as network policies, service accounts, and role-based access control (RBAC). Network policies allow you to control network traffic between pods, while service accounts and RBAC provide granular control over user access to Kubernetes resources.

Give an example of how Kubernetes can be used to deploy a highly available application?

1. Kubernetes can be used to deploy a highly available application by using features such as replica sets, deployments, and services. By deploying multiple replicas of an application, Kubernetes can ensure that the application is always available even if some of the replicas fail.

What is namespace is kubernetes? Which namespace any pod takes if we don't specify any namespace?

1. A namespace in Kubernetes is a way to organize and isolate resources within a cluster. If you don't specify a namespace, a pod will be created in the default namespace.

How ingress helps in kubernetes?

1. Ingress is a Kubernetes resource that provides an external load balancer for HTTP and HTTPS traffic. Ingress allows you to route traffic to different services based on the URL path or host name.

Explain different types of services in kubernetes?

1. Kubernetes provides different types of services such as ClusterIP, NodePort, and LoadBalancer. ClusterIP provides a virtual IP address for accessing a service within the cluster, while NodePort exposes a service on a port on each node in the cluster. LoadBalancer provides an external load balancer for a service.

Explain the concept of self-healing in Kubernetes and give examples of how it works?

1. Self-healing in Kubernetes refers to the ability of the system to automatically detect and recover from failures. Kubernetes achieves self-healing through features such as liveness probes and readiness probes. Liveness probes ensure that a container is running and healthy, while readiness probes ensure that a container is ready to receive traffic.

How does Kubernetes handle storage management for containers?

1. Kubernetes handles storage management for containers using a feature called Persistent Volumes (PVs). PVs provide a way to store data independently of the containers that use it. Kubernetes also provides storage classes, which allow you to define different types of storage and allocate them dynamically.

How does the NodePort service work?

1. NodePort is a type of service in Kubernetes that exposes a service on a port on each node in the cluster. NodePort allows you to access a service from outside the cluster by accessing any node in the cluster on the specified port.

What is a multinode cluster and single-node cluster in Kubernetes?

A multinode cluster is a Kubernetes cluster that consists of multiple nodes, which can be physical machines or virtual machines. In a multinode cluster, each node runs Kubernetes components such as the kubelet, kube-proxy, and container runtime, and can host one or more pods.

A single-node cluster, on the other hand, is a Kubernetes cluster that consists of a single node. In a single-node cluster, all Kubernetes components run on the same node, and the node can host one or more pods.

Single-node clusters are often used for development and testing purposes, as they are easier to set up and manage. Multinode clusters are typically used in production environments, as they provide better scalability, availability, and fault tolerance.

Difference between create and apply in kubernetes?

In Kubernetes, "create" and "apply" are two different ways to create or update a Kubernetes resource.

When you use the "create" command, you are telling Kubernetes to create a new resource from scratch. If the resource already exists, the "create" command will fail with an error.

When you use the "apply" command, you are telling Kubernetes to create or update a resource based on the configuration file you provide. If the resource does not exist, the "apply" command will create it. If the resource already exists, the "apply" command will update it based on the changes in the configuration file.

The main difference between "create" and "apply" is that "create" always creates a new resource, while "apply" can create or update a resource based on its current state.

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