we need to know if a host is always redirect to another host, e.g. gmail.com => mail.gmail.com
design:
- any http 301 will create an entry for host name normalization, we only support host mapping, not the path part.
- not support meta-refresh within html page.
we need to know if a host is always redirect to another host, e.g. gmail.com => mail.gmail.com
design: