Thread by @TheNJDevOpsGuy

Are you thinking about taking the Certified Kubernetes Administrator (CKA) exam?

A thread 🧵

#kubernetes #devops #docker

If so, ensure that you're comfortable in the following domains:
- Kubernetes storage
- Troubleshooting system components (control planes and worker nodes)
- Pod and other workload scheduling (including high availability)

(cont)

- Cluster architecture (building out clusters using Kubeadm)
- All of the control plane and worker node components (Etcd, Controller, Scheduler, etc.)
- RBAC
- Cluster security
- Kubernetes services and networking

For example, let's talk about the networking part.

Although there are other pieces of the networking stack for Kubernetes, in this explanation, we'll stick to Container Network Interface (CNI).

CNI is the plug-in that allows Pods to communicate with each other by obtaining an IP address. Just like standard networking today with switches and routers, Pods need a way to obtain an IP address.

(cont)

Also, Kubernetes components like Services also need IP addresses and Pods need to be able to communicate with each other.

With a CNI, the control planes and worker nodes will sit in a `NotReady` state because the network is not installed. Also, the CoreDNS Pods will not go into a running state because it needs the CNI.

If you use something like Kubeadm to deploy a Kubernetes cluster (which is used for the test), the Controller, Scheduler, Etcd, API Server, Kube-Proxy, and CoreDNS get deployed as Pods.

This is just a brief example, but as you can see, it's a lot... so I highly recommend:
- Study for at least three months
- Do a lot of hands-on practice (the exam is all hands-on. No multiple choice)

It's definitely a great way to test your knowledge.

If you don't want to take the exam, that's okay. You could just go through the training for it and enhance your Kubernetes skills.