[root@llpwfirewall ~]# cat /etc/dhcpd.conf 
#
# DHCP Server Configuration file.
#   see /usr/share/doc/dhcp*/dhcpd.conf.sample  
#
ddns-update-style interim;
default-lease-time 36000;
max-lease-time 46800;
option routers                  172.20.1.1;
option subnet-mask              255.255.255.0;
option domain-name-servers      172.20.1.1,202.106.0.20;