Matching routes with MVC Routing
===

I have the following URLs

 1. URL/description
 2. URL/Home/Member/description
 3. URL/Home/description

Here are my routes

For #1 above:

     routes.MapRoute(
                    name: "DescriptionNoController",
                    url: "{d}",
                    defaults: new {controller = "Home", action = "Index", d = UrlParameter.Optional}
                    );

For #2 above:

     routes.MapRoute(
                    name: "DescriptionDefault",
                    url: "{controller}/{action}/{d}",
                    defaults: new {controller = "Home", action = "Index", d = UrlParameter.Optional}
                    );

I'm having troubles with #3.

I thought I could do 

     routes.MapRoute(
                    name: "DescriptionDefaultNoAction",
                    url: "{controller}/{d}",
                    defaults: new { controller = "Home", action = "Index", d = UrlParameter.Optional }
                    );

But this creates an endless loop. Basically I want the #3 example to map "home/description" to the Home Controller and Index action. Help would be appreciated!