The value must be a legitimate host name or IP address.
IBM TSO HOMETEST command is one way to determine the valid IP addresses on the Lpar.
Example TSO HOMETEST display:
EZA0619I Running IBM MVS TCP/IP CS VvRr TCP/IP Configuration Tester
EZA9431I FTP.DATA file not found. Using hardcoded default values.
EZA0602I TCP Host Name is: xxxxxxxx
EZA0605I Using Name Server to Resolve xxxxxxxx
EZA0611I The following IP addresses correspond to TCP Host Name: xxxxxxxx
EZA0614I The following IP addresses are the HOME IP addresses defined in PROFILE.TCPIP:
EZA0618I All IP addresses for xxxxxxxx are in the HOME list!
EZA0622I Hometest was successful - all Tests Passed!