What’s going on with the Windows Network Connection Status Icon?

Ever wonder where this little guy gets its information from, be it happy or sad?

	Sad LAN Connection
	Happy LAN Connection
	Sad Wi-Fi Connection
	Happy Wi-Fi Connection

Essentially, a task runs whenever a network configuration change event takes place. This calls a service which first tries to NSLookup www.msftncsi.com, the Microsoft Network Connection Status Indicator site. If this is successful, it then performs an HTTP GET on a simple text file stored on this site.

If these two steps work, it proves that DNS, Routing, and HTTP traffic are all allowed and working.

Now, if you’re on a system that can access certain sites explicitly, like Updates.Microsoft.com then you may still a see a status icon of disconnected, even if your system can get out to the general web. This might be because msftncsi.com remains blocked.

So, the icon is a great indicator of whether or not you have web access for most cases, but not necessarily in high security environments.

Source : http://blogs.technet.com/b/networking/archive/2012/12/20/the-network-connection-status-icon.aspx