Two Server Instances Bind to Same Port on Windows

Description

This problem occurs on Windows XP systems with Enterprise Server software, and is due to a known Windows security flaw rather than a problem with Enterprise Server itself.

The problem occurs when two or more instances of Enterprise 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 or Linux system, a port conflict error is thrown and the second instance fails to start. However, when the two domains are started on Windows 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 instances are running, the Windows netstat command only reports the first instance.

Solution

Be sure to use unique port numbers for all server instances on Windows systems.