Not all networks allow using an external DNS. For example I regularly travel with the train in the Netherlands, and some trains provide wifi. The network interc

Not all networks allow using an external DNS. For example I regularly travel with the train in the Netherlands, and some trains provide wifi. The network intercepts all HTTP requests and forwards the user to a Terms Of Usage page; interception stops after the user has checked the 'I agree' checkbox. For a time I was wondering why even the Terms Of Usage page never shows up; turns out it was because I was using the Google DNS. Removing the custom DNS settings made it work again.