Naming and number convention for AOS/WSDL [AX 2012]

If you have only one AOS instance, the default port for the root WSDL is 8101. However, if you have multiple AOS instances, the port number depends on which AOS is hosting the services. The WSDL port number is generated by adding the AOS ID to the base port number, which is 8100.

You can find the AOS ID by viewing the service name. To view the name, open the Services form in Windows Server, click Start, Administrative Tools, and then click Services. The service name uses the following format: Microsoft Dynamics AX Object Server <version>$<AOSID>-DynamicsAx. For example, the service name that is displayed might be: Microsoft Dynamics AX Object Server 6.0$03 –DynamicsAx. In this case, the port number for the WSDL is 8103.

Reference:

http://msdn.microsoft.com/en-us/library/gg843514.aspx