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In Windows 7, the notification area networking icon will show an error indicator if there is no internet access , and the error icon goes away once there is a successful connection to the internet . Sometimes, if the WiFi connection requires an in-browser authentication step, like on many guest networks in hotels or universities, then the following pop-up bubble appears, saying as much:
How does Windows know whether or not it has a successful internet connection?
Presumably it is checking some online Microsoft service to see whether it has a successful connection, gets redirected to some other page, or doesn't get any response at all, but I haven't seen anywhere that this process or the services used are documented. Can anybody explain how this works? I would prefer answers that refer to facts, rather than just guessing, but if you have a really good guess, then go for it.
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1If it were to check a Microsoft service, how would it get past the in-browser activation step? Or am I misunderstanding you? (+1 btw, interesting question) – slhck – 2011-05-02T08:14:21.643
@slhck: That's the point of it checking: if it can't access the service properly, but its attempt gets some response, it presumes that there might be an in-browser step. If there's no response at all, it assumes there's just local access. I'm just not sure how exactly that process works. I've updated my question to be a bit more clear (hopefully). – nhinkle – 2011-05-02T08:18:04.057
@nhinkle I have no Windows PC but maybe somebody can fire up Wireshark to see what the machine actually does in such a case. – slhck – 2011-05-02T08:23:48.957
When the error indicator says that there is no internet access, open the network troubleshooter. While the troubleshooter runs you can clearly see a step "Trying to connect to Microsoft.com". So my guess is that it uses a service. – Mayank – 2011-05-02T08:28:06.327