Error on ASP.NET Websites. Connection Timeout

Question

I have suddenly got this error on a couple of my sites, and I'm not sure what the problem is. These sites have been up and runnnig for over 2 years now and this is the first time I'm seeing this error.

"A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond XX.XX.XXX.XXX:80"

The stack trace is as follows.

[SocketException (0x274c): A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond XX.XX.XXX.XXX:80]
   System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) +239
   System.Net.Sockets.Socket.InternalConnect(EndPoint remoteEP) +35
   System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception) +224

[WebException: Unable to connect to the remote server]
   System.Net.HttpWebRequest.GetRequestStream(TransportContext& context) +1867457
   System.Net.HttpWebRequest.GetRequestStream() +13
   Controls_IpConfigInner.stripConfig(String strClientIp) +136
   Controls_IpConfigInner.Page_Load(Object sender, EventArgs e) +86
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +99
   System.Web.UI.Control.LoadRecursive() +50
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627

The trace tells me it has got something to do with sockets, but there is no socket programming.

Answer 1

You aren't using a socket directly, but you are making a remote web request which uses a socket internally because that is how one does networking stuff on most platforms. Since there is a networking issue you see the socket exception at the end of the day.

That error translates to "I could not open a connection to the remote server. Check the address, make sure it is listening on the appropriate port and make sure we aren't firewalled please."