Kubernetes Interview Questions

Kubernetes Interview Question for Beginners :

What is Kubernetes? 

Kubernetes is an open-source holder orchestration instrument or framework which is utilized to computerize functions, for example, the administration, observing, scaling, and arrangement of containerized applications. It is utilized to handily deal with a few compartments (since it could  deal with gathering of containers), which accommodates intelligent units which can be found and managed.

1. What does the node status include? 
A node status has components like Condition, Address, Capacity, and Info.

2. Define K8
K8 is a different term used for Kubernetes.

3. Explain Daemon sets.
A Daemon set is a bunch of pods that operates just a single time on a host. They are utilized to have layer ascribes like a network or for observing a network, that you will not have to operate on a host more than once. 

4. Explain a Namespace in Kubernetes
Namespaces are utilized for partitioning cluster resources between various clients. They are intended for conditions where there are numerous clients spread across undertakings or groups and give an extent of assets. 

5. Define Kube-proxy
Kube-proxy is an execution of a load balancer and network intermediary utilized to help administration deliberation with other systems administration tasks. Kube-proxy is liable for guiding traffic to the correct compartment dependent on IP and the port number of approaching solicitations.

6. Explain Google Container Engine. 
The Google Container Engine is an open source management platform customized for Docker compartments and clusters to offer help for the groups which operate in Google public cloud services. 

7. Which process operates on Kubernetes Master Node? 
The Kube-api interface server operates on the master node and serves to scale the arrangement of more instances. 

8. Define GKE 
Google Container Engine (GKE) is a management platform which supports the clusters and Docker containers which functions within the public cloud services of Google.

9. What are ClusterIPs? 
The ClusterIP is the default Kubernetes administration which offers a service inside a group (with no outside access) that other applications inside your cluster can get to. 

10. What are NodePorts in Kubernetes? 
The NodePort service is the most basic method to avail external traffic directly to your service. It opens a particular port on all Nodes and transfers any traffic deployed to this port to the service.

11. What is a headless service? 
A headless service is utilized to interface with administration revelation mechanisms without being attached to a ClusterIP, in this manner permitting you to straightforwardly arrive at pods without getting to them through an intermediary. It is helpful when neither load adjusting nor a solitary Service IP is required.

12. How could you avail a static IP for a Kubernetes load balancer? 
A static IP for the Kubernetes load balancer could be accomplished by altering DNS records as the Kubernetes Master could relegate another static IP address. 

13. Explain different types of controller managers?
The primary controller managers that could operate on the master node are the namespace controller, endpoints controller, service accounts controller,  token controller, node controller, and replication controller.

14. Explain Kubernetes controller manager 
The controller manager is a daemon which is utilized for installing center control loops,  Namespace creation, and trash collection. It empowers the functioning of different cycles on the master node despite the fact that they are ordered to function as a solitary cycle. 

Kubernetes Interview Questions for Intermediate:

1. Define a pod in Kubernetes.
Pods are significant level structures that wrap at least one container. This is on the grounds that containers are not operated straightforwardly in Kubernetes. Containers in a similar pod share a localized network and similar assets, permitting them to effortlessly connect with different holders in a similar pod as though they were on a similar machine, simultaneously keeping a level of separation.

2. Define a node in Kubernetes 
A node is the smallest essential unit of commuting equipment. It indicates a solitary machine in a cluster, which can be an actual machine in a virtual machine or a server center from a cloud supplier. Every machine could substitute some other machine in a Kubernetes cluster. The expert in Kubernetes controls the nodes having holders. 

3. Relationship between Docker and Kubernetes 
Docker, an open-source platform utilized to deal with software advancement. Its fundamental advantage is that it bundles the settings and conditions which the software/application requires to operate into a compartment, which considers transportability and a few different benefits. Kubernetes considers the manual connecting and orchestration of a few containers, functioning on various hosts that have been made utilizing Docker.

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4. Explain orchestration in software and DevOps? 
Orchestration alludes to the joining of various administrations that permits them to computerize measures or synchronize data in an ideal manner. For instance, if you have six or seven microservices for an application to function. When you place them in discrete compartments, this would unavoidably make hindrances for correspondence. Orchestration would aid in such a circumstance by empowering all administrations in individual containers to work flawlessly to achieve a solitary objective. 

5. Explain Kubectl. 
Kubectl is a CLI or command line interface which is utilized to run commands against Kubernetes groups. All things considered, it commands the Kubernetes cluster supervisor through various methods and handles commands on the Kubernetes part.

6. How to operate Kubernetes locally?
Kubernetes could be operated locally utilizing the Minikube tool. It operates a single-node cluster in a VM (virtual machine) on the PC. Thus it provides the ideal method for users who have just begun learning Kubernetes.

7. Define Heapster 
A Heapster is a performance observing and measurements collection framework for information gathered by the Kublet. This aggregator is locally upheld and operates like some other unit inside a Kubernetes cluster, which permits it to find and inquiry utilization information from all the nodes inside the cluster.

8. Point out the tools which are utilized for container monitoring?
Tools which are utilized for container monitoring are:

• Grafana
• cAdvisor
• Heapster
• InfluxDB
• Prometheus

9. Explain etcd 
Kubernetes utilizes etcd as an appropriated key-esteem store for all of its information, containing metadata and configuration information, and permits nodes in Kubernetes bunches to peruse and compose information. In spite of the fact that etcd was intentionally developed for CoreOS, it likewise deals with an assortment of operating systems (e.g., BSB, Linux, and OS X) since it is an open-source. Etcd indicates the condition of a cluster at a particular point and is a sanctioned center for state management and cluster coordination of a Kubernetes cluster. 

10. Define Kubelet 
The kubelet is an administration specialist which controls and keeps a bunch of pods  by looking for pod specs through the Kubernetes API server. It protects the pod lifecycle by guaranteeing that a given arrangement of containers are on the whole functioning as they ought to. The kubelet operates on each node and empowers the correspondence between the master and slave nodes.

11. Explain the different services available in Kubernetes
Different types of Kubernetes services include: 

• Cluster IP service
• Node Port service
• External Name Creation service and 
• Load Balancer service

12. Explain the different security measures recommended for Kubernetes
Instances of standard Kubernetes safety measures incorporate characterizing asset quantities, uphold for evaluating, limitation of etcd access, ordinary security updates to the climate, network division, meaning of severe asset strategies, consistent checking for security weaknesses, and utilizing pictures from approved storehouses.

13. What are clusters of containers?
A cluster of containers is a bunch of machine components that are nodes. Clusters start explicit courses so the containers functioning on the nodes can converse with one another. In Kubernetes, the container motor facilitates the API server. 

14. Define LoadBalancer in Kubernetes
The LoadBalancer service is utilized to open administrations to the web. A Network load balancer, for instance, makes a solitary IP address which advances all traffic to your service. 

15. Disadvantages of Kubernetes

• Kubernetes dashboard isn't as useful as it ought to be 
• Security isn't viable. 
• It is intricate and can diminish profitability 
• Kubernetes is more costlier than its other options.

Kubernetes Interview Questions for Experienced:

1. Give the main differences between Kubernetes and the Docker Swarm.
Docker Swarm is Docker's local, open-source container arrangement platform which is utilized to group and schedule Docker containers. Swarm varies from Kubernetes in the accompanying manners: 

• Docker Swarm is more advantageous to set up however it doesn't have a robust group, while Kubernetes is more muddled to set up yet the advantage of having the affirmation of a powerful cluster.
• Docker Swarm can't perform auto-scaling as Kubernetes does; nonetheless, Docker scaling is multiple times quicker than Kubernetes.
• Docker Swarm does not have a GUI, Kubernetes have a GUI as a dashboard.
• Docker Swarm does programmed load adjusting of traffic between the containers in a cluster, while Kubernetes needs manual intercession for load adjusting such traffic.
• Docker requires outsider apparatuses like ELK stack for logging and checking, but Kubernetes has incorporated tools for the equivalent. 
• Docker Swarm can impart storage volumes to any compartment effectively, while Kubernetes can just impart storage volumes to holders in a similar pod.
• Docker can send moving updates yet can't convey programmed rollbacks; Kubernetes can convey moving updates just as programmed rollbacks.

2. Why use Kubernetes?
Kubernetes is utilized on the grounds that: 

• It causes you to evade vendor lock issues as it can utilize any vendor explicit APIs or administrations aside from where Kubernetes gives a reflection, e.g., load balancer and capacity. 
• Kubernetes can run on-premises exposed metal, OpenStack, Azure, public clouds Google, AWS, and so on.
• It will empower applications which should be delivered and refreshed with no vacation. 
• Kubernetes permits you to guarantee those containerized applications operate where and when you need and assist you with discovering assets and apparatuses which you need to work.

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3. What is the function of clusters in Kubernetes?
Kubernetes permits you to authorize the necessary state management by taking care of cluster services of a particular setup. At that point, these cluster administrations operate that configuration in the foundation. The accompanying steps are associated with the method: The deployment document includes all the setups to be taken care of into the cluster administrations. The deployment document is taken care of into the API. Presently, the cluster services plan the pods in the climate. Cluster benefits likewise guarantee that the correct number of pods are operating. Along these lines, the Kubernetes cluster is basically composed of the API, the worker nodes, and the Kubelet cycle of the nodes.

4. Explain the difference between application deployment on hosts and deployment on containers. 
At the point when you send an application on hosts, the bit of the operating system permits numerous libraries to be introduced on it. All the apps share the different libraries present on that operating framework. Nonetheless, the architecture of sending applications on compartments is somewhat unique. In the containerized design, the kernel is the solitary thing common between the applications. Different applications can't infringe upon the libraries and binaries required by one application. Thus, they exist in seclusion from the remainder of the framework. For instance, on the off chance that a specific application needs Python, at that point just that application will gain admittance to it.

5. Explain the function of the Kubernetes Controller Manager.
In Kubernetes, different methods are operating on the master node, and they are accumulated together as the Kubernetes Controller Manager. It is a daemon which installs regulators, including the given below: 

• Replication Controller: Maintains pods for each replication object 
• Node Controller: Manages the status, mainly, making, refreshing and erasing nodes
• Endpoint controller: Maintain the endpoint objects (pods and administrations)
• Administration record and token regulator: Concerned with the default records and API access tokens for new namespaces 

6. Characteristics of Kubernetes
The characteristics of Kubernetes are:

• Self-Healing Capabilities
• Automated Scheduling
• Application-centric management
• You could make predictable infrastructure
• Automated rollouts & rollback
• Offers a higher density of resource utilization
• Horizontal Scaling & Load Balancing
• Provides enterprise-ready features
• Auto-scalable infrastructure
• Provides environment consistency for testing, development, and production.
• Infrastructure is lightly coupled to each segment and can act as a separate unit.

7. What is the function of a load balancer? 
A load balancer gives a standard method to convey network traffic among various backend administrations, subsequently boosting adaptability. Contingent upon the workplace, there can be two kinds of load balancer, Internal or External. The Internal Load Balancer can naturally adjust the load and distribute the necessary configuration to the pods. Then again, the External Load Balancer directs the outside load traffic to the backend pods. In Kubernetes, the two load adjusting techniques work through the kube-proxy highlight. 

8. Explain container resource monitoring.
Concerning clients, it is truly critical to comprehend the execution of the application and asset use at all the diverse abstraction layers, Kubernetes calculated the administration of the cluster by making reflection at various levels like containers, pods, administrations, and entire cluster. Presently, each level can be checked and this is only Container resource monitoring. The different container resource monitoring tools are as per the following: 

IMAGE 

9. Define Ingress network.
Ingress network is an assortment of rules which goes about as a section highlighting the Kubernetes cluster. This permits inbound associations that can be arranged to give benefits remotely through load balance traffic, reachable URLs, or by providing name-based virtual facilitating. In this way, Ingress is an API object which oversees outer admittance to the services in a cluster, generally by HTTP, and is the most remarkable method of uncovering administration.

10. List the uses of GKE
GKE (Google Kubernetes Engine) uses are given below: 

• It very well may be utilized to make docker container clusters
• Resize application regulators 
• Update and redesign the clusters of container
• Investigate clusters of the container. 
• GKE can be utilized to make a replication regulator, occupations, load balancer, administrations, container pods

11. Explain federated clusters
Different Kubernetes clusters can be overseen as a solitary cluster with the assistance of federated clusters. Thus, you can make various Kubernetes bunches inside a data center/cloud and use organization to control/oversee them all at one spot. 

The federated clusters can accomplish this by doing the accompanying two things. Allude to the below outline.

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12. Function of kube-apiserver and kube-scheduler 
Kube-apiserver is the front end of the master node control board which uncovers all the segment APIs. It builds up correspondence between Kubernetes nodes and master segments. The kube-scheduler deals with the remaining workload of the worker nodes. It monitors asset usage to guarantee that the scheduling is done on reasonable nodes. 

13. Explain the requirement for Container Orchestration?
Consider you have 5-6 microservices for a solitary application executing different functions, and all these microservices are put inside compartments. Presently, to ensure that containers converse with one another we require container orchestration. 

IMAGE 

As should be obvious in the above chart, there were additionally numerous difficulties that came into place without the utilization of containers orchestration. In this way, to beat these difficulties the container orchestration came into place.

14. Labels and Annotations in Kubernetes
Label in Kubernetes is a significant label word which can be connected to Kubernetes objects to create them as a part of a gathering. It can be utilized for chipping away at various cases for management or steering purposes. For instance, the controller based items use labels to check the pods that they ought to work on. Microservices utilize labels to comprehend the structure of backend pods they should route demands to. Labels are key-esteem sets. Every unit could have more than one label, however every unit can just have one passage for each key. Key is utilized as an identifier, yet furthermore can characterize objects by different models dependent on advancement stage, public availability, application variant, and so on. Annotations connect subjective key-esteem data to a Kubernetes object. Then again labels ought to be utilized for important data to coordinate a pod with determination measures, annotations contain less organized information. Annotations are a method of adding more metadata to an article that isn't useful for determination purposes.

15. Explain the main components of Kubernetes architecture.

The two primary components include the master node and the worker node. Each of its components has individual components in them. The two segments have numerous in-fabricated administrations inside them. For instance, the master part has the kube-scheduler, kube-controller-manager, etcd, and kube-apiserver. The worker node has administrations like kubelet, container runtime, and kube-proxy functioning on every node.

Conclusion
Thus, by experiencing the above questions you can pick up a fundamental impression of the frequently asked Kubernetes interview questions that you can expect in the interview panel. Aside from the Kubernetes interview questions referenced above, you can locate a wide cluster of hotspots for nitty gritty interview questions and answers. You can utilize such sources for picking up a comprehension of each Kubernetes interview question.