Docker and Kubernetes

What a container is at the level of the Linux kernel, how it differs from a virtual machine, and how images are stored in layers and shared through registries.

The Dockerfile instructions, how the build cache works, and how to build images that are small, fast to rebuild and do not run as root.

How to run containers day to day: publishing ports, Docker networks, keeping data in volumes and bind mounts, restart policies, and running several containers together with Docker Compose.

The parts of a Kubernetes cluster, what each control plane and node component does, and how controllers keep the cluster matching the state you asked for.

The objects that run your containers, when to use each one, and how Deployments roll out new versions without downtime.

How pods find and reach each other inside a cluster, how traffic from outside gets in, and how NetworkPolicy limits who can talk to whom.

How settings and credentials get into pods, why Secrets need extra protection, and how pods get storage that outlives them.

How Kubernetes decides where pods run, how CPU and memory requests and limits work, and how the cluster grows and shrinks pods and nodes with demand.

How to read the common pod failure states, what probes do when they fail, and which kubectl commands find the cause.