Chapter 5: Kubernetes Networking

1. Pods running on a node must be able to communicate with all Pods on all nodes (including the Pod's node) without NAT and explicit port mapping. All Kubernetes components running on a node, for example, kubelet or system daemons/services, must be able to communicate with all Pods on that node.

2. You can use Flannel with host-gw only if there is Layer 2 (L2) connectivity between the nodes in the cluster. In other words, there cannot be any L3 routers between the nodes.
3. A NodePort Service is implemented as a ClusterIP Service with the additional capability of being reachable using any cluster node IP address and a specified port. To achieve that, kube-proxy exposes the same port on each node from the range of 30000–32767 (which is configurable) and sets up forwarding so that any connections to this port will be forwarded to ClusterIP...