private string LookupDns(string s)
        {
            try
            {
                System.Net.IPHostEntry ip = System.Net.Dns.GetHostEntry(s);

                string result = ip.AddressList[0].ToString();

                for (int i = 1; i < ip.AddressList.Length; ++i)
                    result += ", " + ip.AddressList[i].ToString();

                return result;
            }
            catch (System.Net.Sockets.SocketException se)
            {
                return se.Message;
            }
        }