I'm not familiar with w/e issue of Ubuntu caused `search domains` to end up in your resolv.conf. I'm skeptical it wasn't just a misconfiguration. At any rate, you had a problem with your host configuration.

The kubelet will merge the hosts resolver config with the cluster config to generate a resolv.conf file for the pods it runs, resulting in the issue you described. This can cause other annoying dns issues. It has nothing to do with CoreDNS. The only way I've found to disable this kubelet behavior is to start the kubelet with `--resolv-conf=/dev/null`