Kubernetes Interview Questions

Kubernetes is an open-source technology for deploying, scaling and maintaining containerized applications automatically. The Cloud Native Computing Foundation now maintains it after Google initially built it  Kubernetes is designed to be highly scalable, allowing you to easily deploy and manage containerized applications in a cluster of machines. Thousands of users and developers support it in both production and development environments. In this list of Kubernetes interview questions and answers, we will cover a range of topics related to the use and administration of Kubernetes, including deployment, scaling, networking, security, and more.

We have divided the questions into 3 parts:

• Kubernetes Interview Questions for Freshers
• Kubernetes Scenario Based Interview Questions
• Kubernetes Interview Questions Advanced

Kubernetes Interview Questions and Answers:

Q1) What does Kubernetes do and for what purposes?

Ans: An open-source technology called Kubernetes is used to automatically deploy, scale, and maintain containerized applications. It allows users to define and deploy containerized applications in a declarative way, and it provides a set of tools and APIs for managing and monitoring those applications.

Q2) How does Kubernetes work?

Ans: Kubernetes works by running a cluster of nodes, which can be physical or virtual machines. To deploy and manage containerized applications, these nodes run the necessary components and processes. Users can define their desired state for their applications using Kubernetes objects, such as pods, deployments, and services. Kubernetes ensures that the actual state of the cluster matches the desired state by continuously monitoring and making changes as needed.

Q3) What are the core elements of a Kubernetes cluster?

Ans: A Kubernetes cluster's essential elements include:

1) Master node: This node runs the control plane components, such as the API server, scheduler, and controller manager, which are responsible for the overall management of the cluster.

2) Worker nodes: These nodes run the applications and processes defined by the user. Their management is overseen by the master node.

3) Etcd: Cluster configuration data is stored in this distributed key-value store.

4) Kubernetes API: This is the primary interface for interacting with the cluster, and it allows users to create, update, and delete objects in the cluster.

Q4) In what ways does Kubernetes orchestrate containers?

Ans: Containerized applications are managed and deployed using Kubernetes APIs and Devops tools. It allows users to define the desired state of their applications, such as the number of replicas and resource limits, and it automatically manages the actual state of the cluster to match the desired state. This includes scheduling containers on the appropriate nodes, scaling up or down based on resource usage, and rolling out updates or rollbacks as needed.

Q5) In Kubernetes, what is a pod?

Ans: Pods are the smallest deployable Kubernetes units. It is a logical host for one or more containers, and it represents the basic execution unit for applications in a Kubernetes cluster. Pods are transient objects that can be generated and removed as required.

Q6) What is a node in Kubernetes?

Ans: A Kubernetes cluster's worker machines are known as nodes. It can be a physical or virtual machine, and it runs the necessary components and processes to manage and deploy containerized applications.

Q7) What is a deployment in Kubernetes?

Ans: A deployment is a high-level object that represents a group of replicas of a specific application. It allows users to declaratively define their desired state for the application, such as the number of replicas and the container image to use, and it automatically manages the actual state of the replicas to match the desired state. Deployments also provide rolling update and rollback functionality.

Q8) What is a replica set in Kubernetes?

Ans: A replica set is a lower-level object in Kubernetes that is responsible for maintaining a specific number of replicas of a pod. It ensures that the specified number of replicas are always running, and it can replace failed or deleted pods as needed.

Q9) What is a service in Kubernetes?

Ans: A service is an abstract way to expose an application running in a Kubernetes cluster to other parts of the cluster or to the outside world.

Kubernetes Scenario Based Interview Questions

Q10) What is the Etcd distributed key-value store and what is it used for in Kubernetes?

Ans: Etcd is a distributed key-value store that is used to store the configuration data for a Kubernetes cluster. It is used to store information about the state of the cluster, such as the current set of pods and services, as well as any changes to the cluster. Etcd is a critical component of a Kubernetes cluster as it provides the persistent storage needed to maintain the state of the cluster.

Q11) What is a label in Kubernetes and how is it used?

Ans: A label in Kubernetes is a key-value pair that is attached to an object (such as a pod or a deployment) and is used to organize and identify objects. Labels can be used to group objects together and to specify criteria for selecting a group of objects. For example, you could use labels to specify the environment (e.g., production, staging) or the version of an application that a group of pods is running.

Q12) What is a namespace in Kubernetes and how is it used?

Ans: A namespace in Kubernetes is a virtual environment that is used to group resources together. Each namespace has its own set of objects (e.g., pods, services, etc.), and resources within a namespace are isolated from resources in other namespaces. Namespaces are useful for separating resources that belong to different environments (e.g., production, staging) or teams.

Q13) What is an ingress in Kubernetes and how is it used?

Ans: An ingress in Kubernetes is a collection of rules that allow inbound connections to reach the cluster. It is used to expose the services in a cluster to external clients, such as users accessing a web application. An ingress can be configured to provide load balancing, SSL termination, and name-based virtual hosting.

Q14) What is a persistent volume in Kubernetes and how is it used?

Ans: A persistent volume (PV) in Kubernetes is a piece of storage that is not tied to a specific pod or node. It is used to provide persistent storage for pods, allowing them to retain data even if the pod is deleted or moved to another node. PVs are typically provisioned by an administrator and are then claimed by a persistent volume claim (PVC). The PV and PVC are used to mount storage to a pod.

Q15) How does Kubernetes handle application scaling?

Ans: Kubernetes makes it easy to scale your applications up or down based on demand. You can use the “kubect1” command-line tool or the Kubernetes API to adjust the number of replicas of a deployment, and Kubernetes will automatically spin up or tear down the necessary containers. You can also set up autoscaling rules that will automatically adjust the number of replicas based on metrics like CPU usage or request rate.

Q16) How does Kubernetes handle application upgrades and rollbacks?

Ans: Kubernetes provides several mechanisms for upgrading and rolling back applications. You can use the “kubect1 set image” command to update the container image for a deployment, and then use the “kubect1 rollout” command to perform a rolling update, which will gradually replace the old containers with the new ones while minimizing downtime. If you need to roll back to a previous version, you can use the “kubect1 rollout undo” command to revert the deployment to a previous revision.

Kubernetes Interview Questions for Experienced:

Q17) How does Kubernetes handle network traffic and service discovery?

Ans: Kubernetes uses a feature called "service discovery" to make it easy for applications to communicate with each other. When you create a service in Kubernetes, it is given a DNS name and an IP address, and any containers that are part of that service can use the DNS name to communicate with each other. Kubernetes also provides built-in load balancing, so that if you have multiple replicas of a service, incoming traffic will be evenly distributed across them.

Q18) How do you troubleshoot issues in a Kubernetes cluster?

Ans:

• First, I would gather as much information as possible about the issue, including any relevant logs or error messages.
• Next, I would use the “kubect1” command-line tool to inspect the status of the cluster and the individual components (pods, deployments, etc.) to check whether they have any problems.
• If necessary, I would use tools like “kubect1” describe and “kubect1” logs to get more detailed information about the issue.
• Depending on the issue, I might also need to use additional tools like “strace”, “tcpdump”, or “1sof” to dig deeper into the problem.

Q19) How do you monitor the performance of a Kubernetes cluster?

Ans: There are several tools and techniques that I would use to monitor the performance of a Kubernetes cluster:

• First, I would use the “kubect1 top” command to get a high-level view of the resource usage for the different components in the cluster (pods, nodes, etc.).
• Next, I would use tools like “kubect1 describe” and “kubect1 logs” to get more detailed information about the resource usage and performance of individual pods or deployments.
• I would also use monitoring tools like Prometheus or Grafana to collect and visualize metrics like CPU and memory usage over time, and set up alerts to notify me of any issues.

Q20) How do you secure a Kubernetes cluster?

Ans: There are several steps I would take to secure a Kubernetes cluster:

• First, I would ensure that all nodes in the cluster are running the latest security patches and updates.
• Next, I would use network segmentation and firewall rules to limit access to the cluster and control the flow of traffic between the different components.
• I would also use role-based access control (RBAC) to define granular permissions for different users and resources in the cluster.
• Additionally, I would use security tools like AppArmor or SELinux to enforce security policies at the kernel level, and implement encryption for sensitive data at rest and in transit.

Q21) How do you perform a blue-green deployment with Kubernetes?

Ans: A blue-green deployment is a technique for rolling out updates to an application without downtime. To perform a blue-green deployment with Kubernetes, I would follow these steps:

• First, I would create a new version of the application (the "green" version) and deploy it alongside the current version (the "blue" version).
• Next, I would use a load balancer or a service in Kubernetes to route a portion of the traffic to the green version, and gradually increase the percentage over time.
• If the green version is working correctly, I would switch the load balancer or service to route all traffic to the green version, and then scale down or delete the blue version.
• If there are any issues with the green version, I can quickly roll back the deployment by switching the traffic back to the blue version.

Q22) How do you ensure high availability in a Kubernetes cluster?

Ans: There are several ways to ensure high availability in a Kubernetes cluster, including:

• Using multiple availability zones or regions to spread out the cluster and reduce the impact of failures
• Configuring pods and services with liveness and readiness probes to detect and recover from failures
• Using replica sets or deployments to ensure that a specified number of replicas of a pod are always running
• Using persistent volumes and persistent volume claims to ensure that data is not lost if a pod fails

Q23) How do you handle persistent storage in Kubernetes?

Ans: Persistent storage can be handled in Kubernetes through the use of persistent volumes (PVs) and persistent volume claims (PVCs). PVs represent actual storage resources, while PVCs are requests for those resources. When a PVC is created, it is dynamically matched to an available PV. The PV and PVC are then used to mount storage to a pod.

Q24) How do you scale a Kubernetes application?

Ans: There are several ways to scale a Kubernetes application, including:

• Scaling the number of replicas in a deployment using the kubect1 scale command
• Scaling the resources (e.g., CPU, memory) of a deployment using the kubect1 scale command and specifying the resource limits
• Using horizontal pod autoscaling to automatically scale the number of replicas based on CPU or memory usage
• Using vertical pod autoscaling to automatically increase the resources allocated to a pod based on resource usage.

Conclusion:

Kubernetes is a powerful platform for managing containerized applications at scale. It provides a range of features and tools for deployment, scaling, networking, and security, and it is widely used in both production and development environments. If you are preparing for a Kubernetes interview, it is important to have a good understanding of the core concepts and components of the platform, as well as the skills and experience needed to effectively deploy and manage applications on Kubernetes. We hope that this list of Kubernetes interview questions and answers will serve as a helpful resource as you prepare for your interview.