You can set the Application
controller and the Admin
method as the default controller and action, using parameter defaults:
routes.MapRoute(
"Default", // Route name
"{action}", // URL with parameters
new { controller = "Application", action = "Admin" }
);
If this is your last route, it will match any request that does not have a controller name and an action name in it. In this particular example, even a request without an action will execute your Admin
action, since it's the default action.
Note that routes with parameter defaults can create strange behavior in your existing routes, if you have any. You can always use the ASP.NET MVC Routing Debugger to test which routes match a given URL.