Small script I used for testing LB

test.js

var page = require('webpage').create();
var system = require('system');

var args = system.args;
var navigateTo = null;

if (args.length === 1) {
  console.log('Please provide a URL to navigate to.');
  phantom.exit()

} else {
  navigateTo = args[1];
}

phantom.cookiesEnabled = true;
page.cookies = phantom.cookies;

page.onResourceReceived = function(response) {
  for (var i = response.headers.length - 1; i >= 0; i--) {
    if (response.headers[i].name == 'X-Instance' || response.headers[i].name == 'X-Server') {
      var logStr = response.headers[i].value + "\t\t(" + response.url + ")";
      console.log(logStr);
    }
  }
};


page.open(navigateTo, function(status) {
 var cookies = page.cookies;

 for(var i in cookies) {
  if(cookies[i].name == "b1P") {
    console.log(cookies[i].name + '=' + cookies[i].value);
  }
}
phantom.exit();
});