This problem only occurs on Windows 2000/XP systems with the Application Server Enterprise Edition (not Platform Edition) software, and is due to a known Windows security flaw rather than a problem with the Application Server itself.
The problem occurs when two or more instances of the Application Server are created using the same port number for the instanceport option; for example:
asadmin create-domain -adminport 5001 <options\> -instanceport 6001 <domain\ asadmin create-domain -adminport 5002 <options\> -instanceport 6001 <domain\>
When the two domains are started on a UNIX/Linux system, a port conflict error is thrown and the second instance fails to start. However, when the two domains are started on Windows 2000/XP, no error is thrown, both server instances start, but only the first instance is accessible at the specified port. When that first server instance is subsequently shut down, the second instance then becomes accessible. Moreover, when both instance are running, the Windows netstat command shows the duplicate listeners as active, but only the first listener can respond to requests.