Do not bind the insecure API service.
If you bind the apiserver to an insecure address, basically anyone who could connect to it over the insecure port, would have unauthenticated and unencrypted access to your master node. The apiserver doesn't do any authentication checking for insecure binds and traffic to the Insecure API port is not encrpyted, allowing attackers to potentially read sensitive data in transit.
Connections to the API server will require valid authentication credentials.
Edit the API server pod specification file '/etc/kubernetes/manifests/kube-apiserver.yaml' on the master node and remove the '--insecure-bind-address' parameter.