code: function (callback) {
      var self = this;
  
      self._request({
        path: urlJoin(_urlPrefix, 'alloweddomains')
      }, function (err, body) {
        return callback(err, body.allowedDomains);
      });
    }
docs: client.getAllowedDomains
  
  @description gets a list of domains that are available in lieu of IP addresses
  when adding nodes to a load balancer
  
  @param {function}        callback