Kubernetes Interview Questions – Part 2 – 13 October 2023

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Kubernetes Interview Questions:

09 October 2023:

What happens if you “pause” a Deployment?

• A) All Deploymet’s Pods will be paused
• B) Deployment will be paused, and changes will not take effect
• C) Kube-apiserver will be paused to accept new Deployments
• D) All traffic to Deployment’s Pods will be paused

When you “pause” a Deployment object, any changes to the deployment will not go live or take effect, especially the rollout mechanism. So, the behaviour is: pausing the deployment, and the result is: pausing the Deployment’s rollouts.

https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#pausing-and-resuming-a-deployment

10 October 2023:

CronJobs will be run based on which timezone?

• A) Based on kube-apiserver timezone
• B) Based on worker node timezone
• C) Based on kube-controller-manager timzeone
• D) Based on kubelet timezone

The CrobJob controller inside the kube-controller-manager component is responsible for running CronJob’s Pods, and as it runs inside the kube-controller-manager, it runs the CronJob based on the kube-controller-manager timezone. From Kubernetes 1.24, a new option timezone is added to allow changing the timezone for every Cron job.

https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/#time-zones

11 October 2023:

What happens if the Pod readinessProbe gets failed?

• A) Pod-to-Pod traffic will not be sent until readinessProbe gets passed
• B) Service-to-Pod traffic will not be sent until readinessProbe gets passed
• C) Pod will stay Pending until readinessProbe gets passed
• D) Pod will be restarted until readinessProbe gets passed

The readinessProbe option helps Kubernetes, Endpoints controller, to find if the Pod is ready to accept connections or not. If the readinessProbe of the Pod fails, the Pod’s IP address will be removed from the corresponding Endpoints object, which means if traffic comes from the Service, the Service will not send the traffic to that Pod.

https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#define-readiness-probes

12 October 2023:

Which components may need to call API in Kubelet?

• A) All components call kube-apiserver, and no one calls kubelet APIs
• B) kube-apiserver may need to call kubelet APIs
• C) kube-controller-manager may need to call kubelet APIs
• D) kube-scheduler may need to call kubelet APIs

Although all components call kube-apiserver to do their jobs, kube-apiserver needs to call kubelet to do two things. kube-apiserver will call kubelet APIs to access Pod’s shell in kubectl exec command and to get Pod’s logs in kubectl logs command.

13 October 2023:

What happens if the Pod livenessProbe gets failed?

• A) Pod-to-Pod traffic will not be sent until livenessProbe gets passed
• B) Service-to-Pod traffic will not be sent until livenessProbe gets passed
• C) Pod will stay Pending until livenessProbe gets passed
• D) Pod will be restarted until livenessProbe gets passed

The livenessProbe job is to ensure the container is healthy, and if it fails, the container keeps restarting until it becomes healthy. Both livenessProbe and readinessProbe should be defined for every container to ensure they work properly.

https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#define-a-liveness-command

Conclusion:

Kubernetes itself is wild. Man vs. Wild in interviews needs deep knowledge, hands-on experience and additional skills to pass. If you want to pass Kubernetes role interviews, read more and do many more with Kubernetes. Our goal in Kubedemy is to help you understand and solve Kubernetes difficulties in all situations.

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