In the bottom right hand corner of your Windows Desktop i.e. the notification area is a great way to determine many problems to issues people come to you with.
"I haven't got mapped drives"
"The network printers say offline"
Silly things that all essentially can be addressed by seeing a red X on the wireless or network adapter.
Now when someone comes in and says "my internet isn't working" and you see the "no connectivity" indicator, you know deep down it means nothing because you can't trust it, especially if you are in an environment that uses a proxy.
So why does it say "no internet connectivity" even though you have it.
Essentially, the network adapter calls to Microsoft to find a file on the internet, if it finds it, it confirms internet connectivity. Nice and easy. If the file is blocked, it can't determine internet is working, even though it might be.
However via a proxy its a pain in the derriere, as for some reason it struggles to find this file. When it struggles to find this file it struggles to activate windows via a KMS connection, the Windows 8 store fails to load and most of the Windows 8 apps fail to work correctly.
In Group Policy you can actually tell your clients what machine to look at to determine whether or not it has internet connection, when it pings the server it accepts that it has an internet connection and KMS and the Windows 8 store and apps start to behave.
The Group Policy is found here:
Computer Configuration -> Network -> Network Connectivity Status indicator -> Specific Corporate DNS Proble Host Address.
Enable this policy and specify the IP address of your router (or server of your choice), essentially if it can see the router you can safely assume, providing your network is working, the computer has internet connection.
It makes that lovely marker over your network adapter vanish and everything starts to work in the way you would expect.