From DSL Speed Test:
Internet Speed Test Diagnostics is a broadband diagnostic tool that helps you quickly perform speed test and troubleshoot common connectivity problems. You can measure both the upload and download speed/bandwidth of your Internet connection. When you have trouble with Internet access, e-mail, VPN, or WIFI or Web proxy, you can run the tests to isolate problems with networking configruation, NIC card, WIFI router, Cable/DSL modem, service provider network, Web server or the applcation itself. It can also show IP network configurations, including IP address, DNS server, DHCP server and local routing table.