If you register a hostname with . at start, then all subdomains will solve to that container/local storage entry
Example
docker run --rm --hostname .mageddo.com nginx:latest
Now all mageddo.com subdomains will solve to that nginx container
$ nslookup site1.mageddo.com
Server: 172.17.0.4
Address: 172.17.0.4#53
Non-authoritative answer:
Name: site1.mageddo.com
Address: 172.17.0.5
$ nslookup mageddo.com
Server: 172.17.0.4
Address: 172.17.0.4#53
Non-authoritative answer:
Name: mageddo.com
Address: 172.17.0.5