NetworkInfo.isConnected() returns true but no connection

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http://stackoverflow.com – I use gar's answer from this StackOverflow post to check internet connection availability. But, I'm not sure if it works correctly. If I turn off WiFi and mobile data connection and run the application, NetworkInfo.isConnected() returns true when there's no connection to the internet available. What's wrong? If I turn airplane mode on, it correctly says no connection. (HowTos)