Someone

class "pxebooters" {
        match if substring (option vendor-class-identifier, 0, 9) = "PXEClient";
}

subnet 138.77.34.0 netmask 255.255.255.0 {
        not authoritative;
}

# Deploy subnet
subnet 192.168.19.0 netmask 255.255.255.0 {
        option domain-name "cqu.edu.au";
        option routers 192.168.19.1;
        option subnet-mask 255.255.255.0;
        option broadcast-address 192.168.19.255;
        pool {
                allow members of "pxebooters";
                next-server 138.77.34.20;
                filename "pxelinux.0";
                range 192.168.19.10 192.168.19.49;
        }
        pool {
                deny members of "pxebooters";
                range 192.168.19.50 192.168.19.127;
        }
        max-lease-time 3600;
        default-lease-time 3600;
}