How does my computer know that it is connected to the Internet?
<p>Sorry for asking such a mundane question, but I'm suddenly curious. If I open the network connections dialog on my Windows machine, it shows me a cute little picture of my computer connecting to a router and then to a globe (labeled Internet). What is Windows trying to connect to in order for it to decide that the computer has Internet connectivity? I assume there is no IP4 address for 'The Internet', so where is it going? Is it just sending a ping to an address back at the Microsoft home office? If that address were to disappear, would my window's machine suddenly decide that it no longer has a route to the Internet? Would Windows boxes that were 'close' to that address incorrectly report that they could get to the Internet when they couldn't. </p>

<p>I'll stop now before this gets too silly. But seriously, what criteria does a Windows box use to determine that it has Internet connectivity? I'm assuming that Linux and iOS systems have an equivalent feature. Do they use the same criteria? </p>