This article describes the VM control and worker nodes needed for the Routing Director and why they are needed.

Nodes are the servers on which the kubernetes cluster is deployed. out of 4 nodes, 3 nodes will be the primary nodes (which will control the kubernetes cluster) and one will be the worker node (which will take instructions from the primary/control nodes).

Kubernetes nodes are the physical or virtual machines that provide the computing resources (CPU, memory, storage) for a cluster, while pods are the smallest deployable units in Kubernetes that run your applications. Pods run on nodes and act as wrappers for one or more containers.

The pods are the units that are running the routing director applications.

The control nodes/primary nodes ensure redundancy and also ensure the deployment of the pods on all the nodes.

Having said that, the control nodes also have pods deployed on themselves as well as the worker node.