Last night, whilst working in the Premier Inn close to the office, I noticed the browser going to an interesting URI after I connected to the hotel Wi-Fi. That URI was http://www.msftconnecttest.com/redirect and a little more research tells me it’s used by Windows 10 to detect whether the PC has an Internet connection or not.
The feature is actually the Network Connection Status Icon (NCSI) and, more accurately, the URIs used are:
- http://www.msftncsi.com/ncsi.txt (for Windows 10 version 1507 and 1511, also known as Threshold 1 and Threshold 2/November update)
- http://www.msftconnecttest.com/connecttest.txt (from version 1607, also known as the Redstone/Anniversary update onwards)
The URI I saw actually redirects to MSN whereas the ones above return static text to indicate a successful connection.
For those who want to know more, there’s a detailed technical reference on TechNet, which dates back to Windows Vista and an extensive blog post on the Network Connection Status Icon.