When our site was promoted to Production recently, we started getting exceptions for Page Not Found errors. The surprising aspect of these errors where the files like robots.txt, xmldata etc… I found a nice blog which explains the best possible routes to ignore while working with ASP.NET MVC.

http://szahariev.blogspot.com/2010/03/aspnet-mvc-best-practices-routes-to.html 

You can also take this list and add it to your list of ignored routes. Happy Coding!!!