Changing domain name of url

Hi,
 
We all know that RequireHttps is not available in WEBAPI so we need to make a custom one.
What I did here is that I took an incoming HTTP URL, Changed the Port to the one created via SSL and changed the scheme to Https. (That only works for One Tier Application.)
 
Now my question is how do I change the domain name ? (Three Tier or Distributed Apps)
 


like : http://www.karma.com
TO
https://www.newkarma.com 

Tried Googling but didnt find anything specific