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?
 </a> | Sad LAN Connection |
 </a> | Happy LAN Connection |
 </a> | Sad Wi-Fi Connection |
 </a> | 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
