c# - リモート名を解決できませんでした: Recaptcha を使用した「www.google.com」

Question

ASP.NET サイトに Recaptcha を使用しています。開発環境ではすべて問題ありませんが、本番環境に公開すると、次のエラーが発生しました。

The remote name could not be resolved: 'www.google.com'
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Net.WebException: The remote name could not be resolved: 'www.google.com'

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[WebException: The remote name could not be resolved: 'www.google.com']
   System.Net.HttpWebRequest.GetRequestStream() +5322142
   Recaptcha.RecaptchaValidator.Validate() in D:\recaptcha-repo-dotnet\library\RecaptchaValidator.cs:134
   Recaptcha.RecaptchaControl.Validate() in D:\recaptcha-repo-dotnet\library\RecaptchaControl.cs:332
   System.Web.UI.Page.Validate() +141
   System.Web.UI.Page.Validate(String validationGroup) +8740369
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +84
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565