Relay Server URL Prefix – the URL
                                prefix to be used when the device client is connecting through Relay
                                Server. The prefix you set depends on whether Relay Server is
                                installed on IIS or Apache.
                                For
                                IIS, this path is relative. Acceptable
                                values
                                include:- For IIS – use/ias_relay_server/client/rs_client.dll.
                                    
 
- For Apache – use /cli/iasrelayserver. 
 
Note: The value
                used in the client application connection for the URL prefix must match what the
                administrator configures in the URL suffix. Otherwise the connection fails. Test
                these value by using the Diagnostic Tool command line utility. See  Diagnostic
                    Tool Command Line Utility (diagtool.exe) Reference  in System
                    Administration.