Unfortunately, I run skydns for service discovery, and having multiple dns servers on the same machine is a PITA. I should note, for anyone considering skydns, that skydns + etcd + docker is circular dependency hell :)
If skydns fails to load its config from etcd, it doesn't terminate, it just continues and emits a warning.
If you are using etcd.discovery.io for your discovery url, you need to have dns working.
At some point, passing multiple --dns to docker didn't cause failover to be working. Or at least, dns resolution was failing in the etcd container, despite the docker daemon having `--dns 127.0.0.1 --dns 8.8.8.8 --dns 8.8.4.4`. I don't even know.
