Something

subnet 192.168.0.0 netmask 255.255.255.0 {
}
host dbox {
hardware ethernet 00:50:9c:44:7c:ee;
fixed-address dbox2;
if exists vendor-class-identifier {
filename "dbox2";
option root-path "/tftpboot/yaddroot";
} else {
filename "u-boot";
}}