Hi
Here's a sample of my dhcpd.conf :
host maillard {
hardware ethernet 00

0:59:CC:F8:B0;
fixed-address maillard;
option broadcast-address 192.168.0.255;
option routers aracaju;
}
Maybe you can use fixed-address 0.0.0.0 so that the dhcp client gets an invalid IP...