modify root URL generated by <%= link_to %>

Is there a way to manually specify the root url that a <%= link_to %>
generates? So i can make an auto generated url that used to go to
mywebsite.myhost.com/comments be go to example.com/comments ?

The reason, if you're wondering is that I have hosting at a site and my
domain forwarded and masked through go-daddy. This means when you go to
example.com you are seeing content on mywebsite.myhost.com but the url
shows up as example.com. The problem comes when you click on a link for
lets say comments, for whatever reason instead of showing
example.com/comments in the url it just shows example.com. If you type
example.com/comments directly into the address bar though, everything
works great you get the content you expect and the url you expect. So
how can i make my <%= link_to %>'s use example.com as the base url
instead of mywebsite.myhost.com???

Still haven't been able to figure this out. Instead i just changed the
nameserver on go-daddy to point at my RoR host's servers. So even though
i can't host the DNS on the same server, i can have the DNS point at my
RoR host server. Learn something new every day!