http://msmvps.com/blogs/shahed/archive/2009/02/11/asp-net-mvc-tips-routing-engine-to-aid-seo-301-redirect-tracking.aspxRouting Library resides in the System.Web.Routing Namespace of the .NET Framework 3.5, which provides us the flexibility to use URLs that has no mapping to a physical file. This means ASP.NET MVC framework provides flexible URL mapping engine and enablesenCommunityServer 2008.5 SP2 (Build: 40407.4157)