How do I configure my DNS to work with Rancher 2.0 ingress?
You aren't dumb, man. This stuff gets complicated. Are you using AWS or GKE? Most methods of deploying kubernetes will deploy an internal DNS resolver by default for intra-cluster communication. These URLs are only useful inside the cluster. They take the form of <service-name>.<namespace>.svc.cluster.local and have no meaning to the outside world.
However, exposing a service to the outside world is a different story. On AWS you may do this by setting the service's ServiceType to LoadBalancer, where kubernetes will automatically spin up an AWS LoadBalancer, and along with it a public domain name, and configure it to point to the service inside the cluster. From here, you can then configure any domain name that you own to point to that loadbalancer.