The configuration for a slave DNS server is practically the same, the only exception will be the individual zone type declarations  specified in /var/named/chroot/etc/named.conf are set to be  “slave“ types and the “masters”  zone option are set to be the master’s IP address.

Example individual zone file on the master looks like this:
zone "rubyninja.org." IN {
type master;
file "etc/zones/db.rubyninja.org";
allow-query { any; };

};

This example individual zone file will be set as this on the slave named.conf configuration file:
zone "rubyninja.org." IN {
type slave;
file "etc/zones/db.rubyninja.org.bak";
allow-query { any; };
masters { MASTER_IP-ADDRESS_HERE; };
};