ASP.Net 4 routing and subdomains

I'm developing a site with ASP.Net 4 which uses routing extensively. it displays pages for each client depending on the route data.

http://localhost/abc/manage/posts/ redirect to posts page of abc client http://localhost/adidas/manage/posts/ redirects to adidas page.

now i need to do this using the subdomain way like adidas.localhost.com. i searched through SOF and found few solutions using MVC.

URL Routing across multiple subdomains

I have added the required wildcard dns, host file changes etc. and i understand that i need to read the hostheader to to determine the client. my question is where do i have to do this check, as im using routing without MVC i don't use MVC controllers. i need to do with ASP.net 4 routing.开发者_运维知识库 can someone give me an idea on this ?