// Mladi, o.z. IPv6/IPv4 research
(function(){
  var a6 = new XMLHttpRequest();
  a6.open('GET', 'https://6.is.ipv6.sk/0052cf8b-9796-48d1-8869-942db2c1ae1f', true);
  a6.send(null);

  var a4 = new XMLHttpRequest();
  a4.open('GET', 'https://4.is.ipv6.sk/0052cf8b-9796-48d1-8869-942db2c1ae1f', true);
  a4.send(null);
})();