Interview questions

Docker is an open platform for packaging and running applications as containers: isolated processes that share the host's Linux kernel (via namespaces and cgroups) instead of needing a full virtual machine. It uses a client-server model: the docker client sends commands over a REST API to the dockerd daemon, which builds images and runs containers from them.

Virtualization abstracts physical hardware: a hypervisor runs virtual machines, each with its own full guest OS. Containerization abstracts the OS layer: containers share the host kernel and isolate apps as processes, making them lighter and faster but with weaker isolation.

TCP is a connection-oriented, reliable protocol that guarantees delivery, ordering, and error-checking at the cost of overhead. UDP is a simple connectionless protocol with no delivery or ordering guarantees, but it's faster and lighter.

A Kubernetes cluster splits into a control plane that makes global decisions and worker nodes that run the workloads. Control plane: kube-apiserver, etcd, kube-scheduler, kube-controller-manager, and the optional cloud-controller-manager; nodes: kubelet, kube-proxy, and a container runtime.

GET requests data (read-only), is safe, idempotent, and cacheable by default, passing parameters in the URL. POST sends data in the request body for the server to process, and is not safe, idempotent, or cacheable by default.