### http://clients1.google.com/generate_204 ### http://clients2.google.com/generate_204 ### http://clients3.google.com/generate_204 ### http://clients4.google.com/generate_204 ### http://clients.l.google.com/generate_204 ### http://connectivitycheck.android.com/generate_204 ### http://connectivitycheck.gstatic.com/generate_204