There was a bug that affects the ability to see zones in the TCP/IP control panel if there are more than 512 zones on the internet. This bug is fixed in Open Transport 1.1, and you should upgrade to it.
The Apple LAN Utility writes the data to the ecfg resource stored in the Ethernet driver itself.
Article Change History:
04 Apr 1996 - Added OT 1.1 fix, and changed distribution.