1. routes.MapRoute("Default", "{controller}/{action}/{id}",
  2. new { controller = "Home", action = "Index", id = "" });
  3.  
  4. protected override void HandleUnknownAction(string actionName) {
  5. //your code here.
  6. }
  7.  
  8. routes.MapRoute("default-action", "{controller}/{actionName}/{id}", new {action="DefaultAction"});
  9.  
  10. public ActionResult DefaultAction(string actionName, string id) {
  11. //handle default action
  12. }