This module have not been published to npmjs, so please install by npm install -g https://github.com/fuminchao/whistle.wildcard-subdomain.git
a.b.c.d.www.a.com # if Unknown
=> b.c.d.www.a.com # if Unknown
===> c.d.www.a.com # if Unknown
====> d.www.a.com # if Unknown
======> www.a.com $ Got it. Then all the above host will be resolved