HttpWebRequest异常无法解析远程名称：“ http”

Question

  System.Net.WebException: The remote name could not be resolved: 'http'
       at System.Net.HttpWebRequest.GetResponse()
       at Helpers.CheckUrl(String url)

我的代码：

try
        {
            if (IsURLValid(url))
            {

                Uri requestUri = new Uri(url);
                HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(requestUri);
                httpWebRequest.Timeout = 30000;
                httpWebRequest.Method = "HEAD";
                httpWebRequest.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:64.0) Gecko/20100101 Firefox/64.0";
                httpWebRequest.Accept = "*/*";
                httpWebRequest.ServicePoint.Expect100Continue = false;
                httpWebRequest.AllowAutoRedirect = false;
                httpWebRequest.MaximumAutomaticRedirections = 4;
                CookieContainer cookies = new CookieContainer();
                httpWebRequest.CookieContainer = cookies;
                HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                MessageBox.Show(httpWebResponse.StatusCode.ToString());

                if(httpWebResponse.StatusCode == HttpStatusCode.OK)
                {
                    return true;
                }
            }
            return false;
        }
        catch (WebException e)
        {
            CommonCodes.WriteLog(e.ToString());
            return false;
}

- 似乎仅在URL为http时才发生异常。有任何想法吗？我想实现url是否有效。我在另一台具有不同DNS的PC上尝试过此问题。 HttpWebResponse行正在生成此异常。验证网址是否有效的最佳方法是什么？

http://1cosmetology.ru/gogyjod/wl62l4f.php?ybmqpftpd=vb-net-grid-control