Ask your system administrator for the symbolic or 4-part dotted numeric TCP/IP address.
Start a 5250 terminal emulator session, log on to the target OS/400, and type
go tcpadm
at the main command line.
The Work with TCP/IP Network Status window appears. Type the number 7 on the main command line.
Under Opt, type the number 3, and then verify that an entry for DRDA appears under Local Port.
If the DRDA port entry does not exist, go to the TCPADM menu and select option 5= Start TCP/IP Servers.
On the next screen, type *DDM in the server application field.