Thanks!!! Ken Nakata & Ted Lemon.
Due to your advice I installed text.tgz and I can make and make install
in /usr/local/dhcp-2.0b1pl26.
 After reboot and #dhclient I can get IP from my ISP's dhcp-server.
IP is 172.16.27.104 on NetBSD/mac68k
How many times boot NetBSD/mac68k ,I get this adress.
 but when I boot MacOS in same machine (and same NIC)
IP is 172.16.30.152. and how many times I boot MacOS,I get this adress.
(but once a month or so ,it's change.)
 It's strange, in same machine,same NetworkInterfaceCard.

Naoki Kobayashi (ntsu9121@dd.catv.ne.jp)