title: HttpClient failing in accessing simple website
body: <p>Here is my code </p>
  
  <pre><code>internal static  void ValidateUrl(string url)
  {
      Uri validUri;
      if(Uri.TryCreate(url,UriKind.Absolute,out validUri))
      {
          using (HttpClient client = new HttpClient())
          {
              try
              {                    
                  HttpResponseMessage response = client.Get(url);
                  response.EnsureStatusIsSuccessful();
              }
              catch (Exception ex)
              {
                    //exception handler goes here 
              }
          }
      }
  }
  </code></pre>
  
  <p>This code when i run it produces this result. </p>
  
  <pre><code>ProxyAuthenticationRequired (407) is not one of the following: 
  OK (200), Created (201), Accepted (202), NonAuthoritativeInformation
  (203), NoContent (204), ResetContent (205), PartialContent (206).
  </code></pre>
  
  <p>All i want to do  is make this code validate whether a given website is up and running. 
  Any ideas?</p>