I've recently created an application called GetGravatar that allows you to update your Twitter profile picture with your Gravatar. Once I'd set up my Windows Azure custom domain name I decided I wanted the web address for this new service site to be without "www" as seems to be all the rage (to keep the web address short). So, I looked at doing a Response.Redirect to catch any attempts to access my domain with "www" in it. I'm very sure that there are better ways of doing this but I added the following to my Site.master file:

    if (Request.Url.ToString().StartsWith("http://www."))
    {
        Response.StatusCode = (int)System.Net.HttpStatusCode.MovedPermanently;
        string responseUrl = Request.Url.ToString().Replace("http://www.", "http://");
        Response.Redirect(responseUrl, true);
    }

So, if somebody types in http://www.getgravatar.com (see it works) or anything with a "www." in the URL they will be redirected to a non-www page. However, the redirect seemed to go to the correct URL but with port 20000. I've no idea why this is so I had to add a special case in to remove the port.

    if (Request.Url.ToString().StartsWith("http://www."))
    {
        Response.StatusCode = (int)System.Net.HttpStatusCode.MovedPermanently;
        string responseUrl = Request.Url.ToString().Replace("http://www.", "http://");
        responseUrl = responseUrl.Replace(":20000", "");
        Response.Redirect(responseUrl, true);
    }

I've not read up to see if this is expected but I thought it was quite unexpected and may be of use to somebody else in the future.