ASP.NET mvc 2 url rewritting or dynamatically create sub domain

Question

i am working on asp.net mvc arch .
 please help me
 
i want url rewriting  how to do it can any one give me code for that
my url is www.fourwarmfeet.com

suppose any user register to the fourwarmfeet.com quick dynamicaly create subdomain on that user name .

suppose rahul will register then the url will created rahul.fourwarmfeet.com

please help me how to do it in anp.net mvc 2


Thanks