GeekLab

After switching my network to a more strict proxy server recently, I found that Windows 7 machines were reporting they weren't connected to the internet anymore. While this is partly true, unauthenticated users can no longer just access http, users don't need to get this message. The probing software is called Microsoft NCSI. What it does, is:

1. perform a DNS lookup on www.msftncsi.com, and request http://www.msftncsi.com/ncsi.txt. This file is a plain-text file that contains only the text Microsoft NCSI.
2. then do a DNS lookup request for dns.msftncsi.com. The answer should be an A-record resolving to 131.107.255.255. If no answer, or a wrong answer is given, NCSI assumes the internet connection is faulty.

I whitelisted www.msftncsi.com in my proxy to allow outbound http-connections from unauthenticated users to this domain.© GeekLabInfo