Tornado.httpserver.HTTPRequest._valid_ip C# (CSharp) Method

        private bool _valid_ip(string ip)
        {
            try
            {
                /*res = socket.getaddrinfo(ip, 0, socket.AF_UNSPEC,
                                         socket.SOCK_STREAM,
                                         0, socket.AI_NUMERICHOST)*/

                var res = Dns.GetHostEntry(ip);

                return (res != null);
            }
            catch(SocketException e)
            {
                //todo what code is this?? if e.args[0] == socket.EAI_NONAME:
                //    return False
                throw;
            }
            return true;
        }
    }