Interview Questions & Answers Complete Guide for Kubernetes

What is Kubernetes?
This is one of the most fundamental Kubernetes interview questions, but it’s also one of the most crucial! Kubernetes is an open-source container orchestration tool or system that automates tasks like containerized application management, monitoring, scaling, and deployment. It is used to easily manage multiple containers (due to its ability to handle container grouping), allowing for the discovery and management of logical units.

What exactly are K8s?
Kubernetes is also known as K8s.

When it comes to software and DevOps, what is orchestration?
Orchestration is the process of integrating multiple services in order to automate processes or synchronize data in a timely manner. Let’s say you need to run an application that requires six or seven microservices. If you put them in separate containers, communication will inevitably become difficult. In this case, orchestration would be useful because it would allow all services in individual containers to work together to achieve a single goal.

What is the relationship between Kubernetes and Docker?
This is one of the most common Kubernetes interview questions, and the interviewer may ask you to describe your experience working with any of them. Docker is a free and open-source software development platform. Its main benefit is that it encapsulates the settings and dependencies that the software/application requires in a container, allowing for portability and a variety of other benefits. Kubernetes enables the manual linking and orchestration of multiple containers running on multiple hosts created with Docker.

What are the main differences between Kubernetes and Docker Swarm?
Docker Swarm is an open-source container orchestration platform developed by Docker that is used to cluster and schedule Docker containers. The following are some of the ways in which Swarm differs from Kubernetes:

  • Docker Swarm is easier to set up but lacks a reliable cluster, whereas Kubernetes is more difficult to set up but provides the assurance of a reliable cluster.
  • Docker Swarm (unlike Kubernetes) does not support auto-scaling; however, Docker scaling is five times faster than Kubernetes.
  • Docker Swarm doesn’t have a graphical user interface (GUI); Kubernetes does, in the form of a dashboard.
  • Docker Swarm automatically balances traffic between containers in a cluster, whereas Kubernetes requires manual intervention.
  • For logging and monitoring, Docker requires third-party tools such as ELK stack, whereas Kubernetes has built-in tools.
  • Docker Swarm allows any container to share storage volumes, whereas Kubernetes only allows containers in the same pod to share storage volumes.
  • Docker can deploy rolling updates but not automatic rollbacks; on the other hand, Kubernetes can deploy both rolling updates and automatic rollbacks.

What’s the difference between running applications on hosts and running them in containers?
The architecture of Deploying Applications includes an operating system. The operating system will have a kernel that contains various libraries required for an application that are installed on the operating system.

The system that runs the containerized processes is referred to as the container host. Because this type is separate from other applications, the applications must include the necessary libraries. Because the binaries are isolated from the rest of the system, they cannot infringe on the rights of other programmes.

What distinguishes Kubernetes from other container management systems?

  • Kubernetes gives the user control over which server will host the container. It will be in charge of deciding how to launch. As a result, Kubernetes automates a variety of manual tasks.
    Kubernetes is a container orchestration system that manages multiple clusters at the same time.
  • It also offers additional services such as container management, security, networking, and storage.
  • Kubernetes keeps track of nodes and containers’ health.
  • Users can easily and quickly scale resources not only vertically but also horizontally with Kubernetes.

What are the most important elements of the Kubernetes architecture?
The master node and the worker node are the two main components of Kubernetes Architecture. Individual components can be found in each of these components.

What is the function of the Kubernetes master node?
The master node is a node that commands and manages a group of worker nodes. In Kubernetes, this type is similar to a cluster. The nodes are in charge of cluster management and the API that is used to configure and manage the collection’s resources. Kubernetes master nodes can run alongside Kubernetes, which is a benefit of dedicated pods.

What is the role of Kube-apiserver?

This type validates API objects and provides configuration data. Pods, services, and replication controllers are all part of it. It also serves as the cluster’s frontend and provides REST operations. All other components interact through this shared frontend cluster state.

In Kubernetes, what is a node?
The smallest fundamental unit of computing hardware is the node. It represents a single machine in a cluster, which could be a physical data centre machine or a virtual machine from a cloud provider. In a Kubernetes cluster, each machine can take the place of any other machine. In Kubernetes, the master is in charge of the nodes that have containers.

What information is contained in the node status?

Address, Condition, Capacity, and Info are the four main components of a node’s status.

What is the purpose of the Kubernetes Master Node?

The Kube-api server process runs on the master node and allows for the deployment of more instances to be scaled.

In Kubernetes, what is a pod?
Instead of a one-liner, try giving a detailed answer to this Kubernetes interview question. High-level structures that wrap one or more containers are known as pods. This is because Kubernetes does not run containers directly. Containers in the same pod share a local network and resources, allowing them to communicate with other containers in the pod as if they were on the same machine while maintaining isolation.

What is the job of the kube-scheduler?
Nodes are assigned to newly created pods by the kube-scheduler.

What is a Kubernetes container cluster?

A cluster of containers is a collection of nodes, or machine elements. Clusters create specific routes for containers running on nodes to communicate with one another. The API server in Kubernetes is hosted by the container engine (not the Kubernetes API server).

What is the Google Container Engine, and what does it do?

The Google Container Engine is an open-source management platform designed specifically for Docker containers and clusters, and it’s used to support clusters in Google’s public cloud services.

What are Daemon Sets, and what do they entail?
A Daemon set is a collection of pods that only run once on a single host. They’re used for host layer attributes like a network or network monitoring, which you might not need to run on the same host multiple times.

What is Kubernetes’ ‘Heapster’?

The interviewer would expect a thorough explanation in response to this Kubernetes interview question. You can explain what it is and how it has benefited you in the past (if you have used it in your work!). For data collected by the Kublet, a Heapster is a performance monitoring and metrics collection system. This aggregator is natively supported and runs in a Kubernetes cluster like any other pod, allowing it to discover and query usage data from all nodes in the cluster.

What exactly is Minikube?
Users can use Minikube to run Kubernetes locally. This procedure allows you to run a single-node Kubernetes cluster on your personal computer, which can run Windows, macOS, or Linux. Users can use Kubernetes for daily development work with this.

In Kubernetes, what is a namespace?
Multiple users can share cluster resources by using namespaces. They’re designed for environments with a large number of users spread across projects or teams, and they offer a variety of resources.

Name the initial namespaces from which Kubernetes starts?

  • Default
  • Kube – system
  • Kube – public

What is the Kubernetes controller manager and what does it do?
The controller manager is a daemon that manages core control loops, garbage collection, and Namespace creation. It allows multiple processes to run on the master node, even if they were all compiled to run as a single process.

What different types of controller managers are there?

The endpoints controller, service accounts controller, namespace controller, node controller, token controller, and replication controller are the primary controller managers that can run on the master node.

What exactly is etcd?
Kubernetes stores all of its data, including metadata and configuration data, in a distributed key-value store called etcd, which allows nodes in Kubernetes clusters to read and write data. Although etcd was designed specifically for CoreOS, it is open-source and thus works on a variety of operating systems (including Linux, BSB, and OS X). Etcd is a canonical hub for state management and cluster coordination in a Kubernetes cluster. It represents the state of a cluster at a specific point in time.

What are the different Kubernetes services?
The following are examples of Kubernetes services:

  • IP service cluster
  • Service for Node Ports
  • Service for generating external names and
  • Service of a load balancer

What exactly is ClusterIP?

The ClusterIP is the default Kubernetes service that provides an internal service that other apps in your cluster can access (with no external access).

What exactly is NodePort?
The NodePort service is the most basic method of directing external traffic to your service. It configures all Nodes to open a specific port and forwards any traffic sent to that port to the service.

What is Kubernetes’ LoadBalancer?

To expose services to the internet, the LoadBalancer service is used. For example, a network load balancer creates a single IP address that directs all traffic to your service.

What exactly is the Ingress network, and how does it function?
An ingress is an object that allows users from outside the Kubernetes cluster to access your Kubernetes services. Users can customise access by creating rules that specify which inbound connections should connect to which services.

How it works- This is an API object that contains the routing rules for managing external users’ access to Kubernetes cluster services via HTTPS/HTTP. Users can easily set up traffic routing rules without having to create a slew of load balancers or expose each service to the nodes.

What exactly do you mean when you say “Cloud controller manager”?
The terms “public,” “private,” and “hybrid cloud” are probably familiar to you. Kubernetes can be run on cloud infrastructure with the help of cloud infrastructure technologies. It is the control panel component of Cloud Controller Manager that contains the cloud-specific control logic. This procedure allows you to connect your cluster to the cloud provider’s API while also separating the elements that interact with the cloud platform from those that only interact with your cluster.

This also allows cloud providers to release features at a different pace than the Kubernetes project as a whole. It’s built around a plugin system that lets different cloud providers integrate their platforms with Kubernetes.

What is Container resource monitoring, and how does it work?
This is the process of gathering metrics and monitoring the health of containerized applications and microservices environments. It aids in the improvement of health and performance while also ensuring that they run smoothly.

What is the difference between a replication controller and a replica set?
In short, a replication controller is referred to as RC. On a pod, it’s a wrapper. The pods, which offer replicas, gain additional functionality as a result of this.

It keeps an eye on the pods and restarts them automatically if they fail. In the event that the node fails, this controller will respawn all of the node’s pods on another node. Unless the pods are wrapped around a replica set, they will not spawn again if they die.

Replica Set, on the other hand, is abbreviated as rs. It’s referred to as a “next-generation replication controller.” This type of support supports equality-based and set-based selectors and has some selector types.

Filtering is possible based on label values and keys. They must meet all of the label constraints in order to match the object.

What is a headless service, and how does it work?
A headless service is used to communicate with service discovery mechanisms without being bound to a ClusterIP, allowing you to access pods directly rather than through a proxy. It’s useful when you don’t need load balancing or a single Service IP.

What are federated clusters, and how do they work?
Cluster federation is the aggregation of multiple clusters to treat them as a single logical cluster. Multiple clusters can be managed as a single cluster in this way. They are able to stay with the help of federated groups. Users can also create multiple clusters within the data Centre or cloud and use the federation to control and manage them all from a single location.

The following steps can be used to perform cluster federation:

The ability to have DNS and Load Balancer with backend from the participating clusters is provided by this cross-cluster service.

Users can synchronise resources across clusters in order to deploy the same deployment set across all of them.

What exactly is Kubelet?
The kubelet is a service agent that monitors the Kubernetes API server for pod specs and controls and maintains a set of pods. It protects the pod lifecycle by ensuring that all of the containers in a given set are up and running. The kubelet is a piece of software that runs on each node and allows communication between the master and slave nodes.

What exactly is Kubectl?
Kubectl is a command-line interface (CLI) for running commands on Kubernetes clusters. As a result, different create and manage commands on the Kubernetes component are used to control the Kubernetes cluster manager.

Give some examples of Kubernetes security best practises.

Defining resource quotas, support for auditing, restriction of etcd access, regular security updates to the environment, network segmentation, definition of strict resource policies, continuous scanning for security vulnerabilities, and using images from authorised repositories are all examples of standard Kubernetes security measures.

What is Kube-proxy and how does it work?
Kube-proxy is a load balancer and network proxy that supports service abstraction as well as other networking operations. Based on the IP address and port number of incoming requests, Kube-proxy is in charge of routing traffic to the appropriate container.

How do you get a Kubernetes load balancer a static IP?
Since the Kubernetes Master can assign a new static IP address, a static IP address for the Kubernetes load balancer can be achieved by changing DNS records.

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