Redirect to page not found page if the url does't exist in mVC

I need to redirect 开发者_如何学Cthe user to page not found page if the url doent exist. if the user copy the url and paste it on the rbowser, the page shows page not found method.

in this i need to redirect the user to page not found page

See this:

How can I properly handle 404 in ASP.NET MVC?

which refers to this:

http://blogs.microsoft.co.il/blogs/shay/archive/2009/03/06/real-world-error-hadnling-in-asp-net-mvc-rc2.aspx