The .asp extension actually tells you nothing other than that the .asp extension was used. On the balance of probabilities, it's likely the case that the site runs on ASP classic on a Windows server, but it could as easily have been moved to, say, the LAMP stack configured (using httpd.conf or .htaccess) to invoke PHP when files bearing the .asp extension are requested. It's not a common thing to do, but it can be the easiest way to solve the link rot problem.