Define API server authorized IP range - Is this only limited to set the context (.config file) for executing kubectl or also in terms of API calls for services hosted on AKS pods? How different is this from nginx ip whitelisting annotation?
The API server authorization IP range feature blocks access from internet to the API server endpoint minus the provided whitelisted IP addresses. Pods within the cluster access the kubernetes API thru the internal service on kubernetes.default.svc.cluster.local. The whitelisting annotation for the nginx ingress controller (https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/annotations/#whitelist-source-range) blocks non-whitelisted IP's from accessing your application running in Kubernetes behind the said ingress controller.