To enable DHCP on a Fanuc that does not show the option in the COMMON settings page, set parameter # 14880 bit 6 to 1 (bits are read from right to left, starting with 0 on the right and 7 on the left), then restart the control. Ensure the Ethernet cable is plugged into CD38A before powering up the machine control. Once powered up, you should see the network settings filled in. 

Known Controls (not exclusive):

16i Model B

18i Model B

21i Model B

0i Model D