You should understand the routing in MVC. This is a simple issue.
Since you are using MVC, this deals with controller and Actions inside.
That is when the request is send, mvc router by default expects a controller and an action with parameters if any.
You can check the above statement inside the App_Start->Routeconfig.cs
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new {controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
This is how the route looks. So when you type Index.aspx/Index.cshtml(if Razor), then it will throw 404 not found error as no such Action exists inside Home controller with Index.aspx name.
I hope this clears your query.
thanks.