Note the rebind functionality is somewhat broken. Twisted's resolution of CNAMES don't really seem to work. While it will return the first cname record.
Subsequent names do not appear to be resolved. Instead we have to use A records :(. Also note most browsers cache the records even with a TTL of 0.
Finally, you can not point the new record to another host that is running on WBTS as the Host: header will cause twisted to just return the original vhosts data.
The record will change back to it's original value after 5 seconds.