C#后台判断一个网站的有效性代码

 try
            {
                System.Net.HttpWebRequest myRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);
                myRequest.Method = "HEAD";
                myRequest.Timeout = 2000;
                System.Net.HttpWebResponse res = (System.Net.HttpWebResponse)myRequest.GetResponse();
                return (res.StatusCode == System.Net.HttpStatusCode.OK);
            }
            catch (System.Net.WebException we)
            {
                System.Diagnostics.Trace.Write(we.Message);
                return false;
            }