Day 9/100daysofK8s

Networking in K8s — Every node must have an interface and be connected to a network. Each node must have it’s own IP Address configured, and MAC address. There are certain ports that must be opened for communication.

kubeapi-server on the master node should accept connections on port 6443 on which all the cluster components(kube-controller, kubelet, kube-scheduler), kubectl, external users, and worked nodes talk to.

Kubelet on all the nodes listens to port 10250. Kube-scheduler requires 10251 to be open. Kube-controller-manager requires port 10252 to be open.

Service on the worker nodes is exposed at port 30000:32767 port.

Etcd server listens to port 2379 and Etcd clients on 2380.

The list of ports that must be open while setting up/debugging networking is also available on K8s documentation page.