IgnoreRoute with file extension is not working in MVC

Question

I have a Content folder and i want all the html files inside the Content folder from getting accessed, so i added this line at the top of the RegisterRoutes() method in the RouteConfig.cs file as follows

 routes.IgnoreRoute("{folder}/{resource}.html");

but still i am able to access the file.

I even tried giving a static value like this

  routes.IgnoreRoute("Content/{resource}.html"); 

and like this

 routes.IgnoreRoute("Content/demo.html");

but still was able to access the file, am i missing some thing, how can i acheive this behaviour.