Library /sys$common/syshlp/net$mgmt_help.hlb about, permanent_changes  *Conan The Librarian (sorry for the slow response - running on an old VAX)

     Just as with NCL, any network management changes you make using NET$MGMT
     will only be retained until the next reboot.  In order to make
     permanent network management changes, you can modify the NCL startup
     scripts by running the SYS$MANAGER:NET$CONFIGURE.COM procedure and using
     the ADVANCED option.  Do not modify the SYS$MANAGER:NET$*_STARTUP.NCL
     scripts directly.  Refer to the Installation and Configuration Manual for
     more information about making permanent configuration changes.