网站登录后台出现这种错误，是哪里的原因?

Server Error in '/' Application.
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The remote name could not be resolved: 'test.fxxtwl.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: 'test.fxxtwl.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: 'test.fxxtwl.com']
System.Net.HttpWebRequest.GetResponse() +1501819
PageAdmin.master_login.xd9dc40336cb754b6() +1939
PageAdmin.master_login.x0c10d87f1cc88e3b() +291
PageAdmin.master_login.x303150620dddbc01() +101
PageAdmin.master_login.x4b531208dfadf445() +144
PageAdmin.master_login.xb99c27096be25a53() +34
PageAdmin.master_login.Page_Load(Object src, EventArgs e) +111
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +15
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +34
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +47
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1061

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Version Information: Microsoft .NET Framework Version:2.0.50727.42; ASP.NET Version:2.0.50727.42

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