option dhcp-max-message-size 2048;
use-host-decl-names on;

option space pxelinux;
option pxelinux.magic      code 208 = string;
option pxelinux.configfile code 209 = text;
option pxelinux.pathprefix code 210 = text;
option pxelinux.reboottime code 211 = unsigned integer 32;

group {
        site-option-space "pxelinux";
        option pxelinux.magic f1:00:74:7e;
        if substring(option vendor-class-identifier, 0, 9) ="PXEClient" {
        append dhcp-parameter-request-list 208, 209, 210, 211;
        }

        filename "pxelinux.0";

                subnet 172.31.20.0 netmask 255.255.255.0 {
                option domain-name-servers 172.31.20.1;
                option time-servers 172.31.20.1;
                option ntp-servers 172.31.20.1;
                option vendor-class-identifier "PXEClient";
                option vendor-encapsulated-options ff;
                option pxelinux.configfile "pxelinux.cfg/default";
                range 172.31.20.10 172.31.20.254;
        }
}