Azure WebJobs PingException，.exe作为控制台应用程序运行良好

我正在尝试构建一个 Azure Web Job 以每 5 分钟检查一次网站的状态。 我将作业构建为运行良好的控制台应用程序。 当它运行时，它将在MySQL数据库中查询网站列表，向该网站提交HTTP请求，然后在MySQL数据库中记录该请求的状态。 就像我说的，从控制台上，这工作得很好。 当我压缩它并将其添加为 Web 作业时，我的程序运行 Ping 以获取响应时间的部分失败了。 我运行 ping 的代码是：

    public ArrayList GetStatusList(ArrayList sites)
    {
        foreach (Website ws in sites)
        {
            HttpWebRequest webRequest = (HttpWebRequest) WebRequest.Create(ws.WebsiteUrl);
            webRequest.AllowAutoRedirect = false;
            HttpWebResponse response = (HttpWebResponse) webRequest.GetResponse();
            ws.HttpStatus = response.StatusCode.ToString();
            Uri uri = new Uri(ws.WebsiteUrl);
            Ping pingClass = new Ping();
            PingReply pingReply = pingClass.Send(uri.Host);
            ws.ResponseTime = pingReply.RoundtripTime;
            ws.WebsiteCheckedDateTime = DateTime.Now;
        }

下面是来自 Azure Web 作业的错误日志：

[02/01/2016 19:33:37 > c91ef2: SYS INFO] Status changed to Stopped
[02/01/2016 19:33:57 > c91ef2: SYS INFO] Detected WebJob file/s were updated, refreshing WebJob
[02/01/2016 19:33:57 > c91ef2: SYS INFO] Status changed to Starting
[02/01/2016 19:33:57 > c91ef2: SYS WARN] 'Always On' doesn't appear to be enabled for this Web App. To ensure your continuous job doesn't stop running when the SCM host is idle for too long, consider enabling 'Always On' in the configuration settings for your Web App. Note: 'Always On' is available only in Basic, Standard and Premium modes.
[02/01/2016 19:33:57 > c91ef2: SYS INFO] Run script 'IsItAlive.exe' with script host - 'WindowsScriptHost'
[02/01/2016 19:33:57 > c91ef2: SYS INFO] Status changed to Running
[02/01/2016 19:33:58 > c91ef2: INFO] Connected to DB, MySQL version : 5.5.45-log
[02/01/2016 19:33:58 > c91ef2: ERR ] 
[02/01/2016 19:33:58 > c91ef2: ERR ] Unhandled Exception: System.Net.NetworkInformation.PingException: An exception occurred during a Ping request. ---> System.ComponentModel.Win32Exception: There are no more endpoints available from the endpoint mapper
[02/01/2016 19:33:58 > c91ef2: ERR ]    at System.Net.NetworkInformation.Ping.InternalSend(IPAddress address, Byte[] buffer, Int32 timeout, PingOptions options, Boolean async)
[02/01/2016 19:33:58 > c91ef2: ERR ]    at System.Net.NetworkInformation.Ping.Send(IPAddress address, Int32 timeout, Byte[] buffer, PingOptions options)
[02/01/2016 19:33:58 > c91ef2: ERR ]    --- End of inner exception stack trace ---
[02/01/2016 19:33:58 > c91ef2: ERR ]    at System.Net.NetworkInformation.Ping.Send(IPAddress address, Int32 timeout, Byte[] buffer, PingOptions options)
[02/01/2016 19:33:58 > c91ef2: ERR ]    at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress, Int32 timeout, Byte[] buffer, PingOptions options)
[02/01/2016 19:33:58 > c91ef2: ERR ]    at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress)
[02/01/2016 19:33:58 > c91ef2: ERR ]    at IsItAlive.BusinessLogic.GetStatusOfSites.GetStatusList(ArrayList sites)
[02/01/2016 19:33:58 > c91ef2: ERR ]    at IsItAlive.Program.Main(String[] args)
[02/01/2016 19:33:58 > c91ef2: SYS ERR ] Job failed due to exit code -532462766
[02/01/2016 19:33:58 > c91ef2: SYS INFO] Process went down, waiting for 60 seconds
[02/01/2016 19:33:58 > c91ef2: SYS INFO] Status changed to PendingRestart

我确信答案就在我面前，但我只是没有足够的经验来理解错误日志。 有人可以帮助我理解为什么我的 Ping 在作为 Web 作业而不是控制台应用程序运行时会导致 Ping 异常吗？

---> System.ComponentModel.Win32Exception: There are no more endpoints available from the endpoint mapper