Rancher Kuberbetes Subnet Allocation

We are trying to set up an On-Premise Rancher Kubernetes environment. I am getting the following two questions from Network team:

  1. What happens if Rancher/Kubernetes exhausts the subnet pool of IP addresses? Does Rancher/Kubernetes allow dynamically add subnet into Kubernetes cluster?

  2. If it is hard to find a subnet within network that is not utilized, so how the Rancher Kubernetes would handle a scenario if have address outside of Kubernetes with same address as something in Kubernetes and front end host has to decide where to send it, will there be any issues? In another word, is there an issue if a server outside of Kubernetes cluster has the same IP as one of containers within Kubernetes cluster?

It would be greatly appreciated if somebody can shed some light on them.

Thanks a lot!