Joseph Herlant
version 1.0.0, 2014-07-24 : Initial version

Tested on CentOS 6.5 in an IPv4 only context.

1. Server-side actions

First, install the bind and bind-utils packages using yum, activate the service and configure iptables to open both TCP and UDP ports 53:

yum -y install bind bind-utils
chkconfig named --levels 35 on
# and ensure named service is stopped
service named off
iptables -I INPUT 5 -m udp -p udp --dport 53 -j ACCEPT
iptables -I INPUT 5 -m tcp -p tcp --dport 53 -j ACCEPT
service iptables save
service iptables restart

Then verify that SELinux will only allow the root and named users to read /etc/named.conf:

# ll -Z /etc/named.conf
-rw-r-----. root named system_u:object_r:named_conf_t:s0 /etc/named.conf

In CentOS 6.5 the service ships with a caching-only configuration by default, so you don’t have a lot to do then. Just comment the IPV6 listening if you don’t use it or the IPV4 if that’s the one you don’t use. Make the service listen on the server interface (not only on local loopback). All these actions are configured in /etc/named.conf which would finally look like this (adapt it to your network of course!):

acl listening_ips {;; };
acl allowed_networks {;; };
acl allowed_slaves {; };

options {
        listen-on port 53 { listening_ips; };
        // Disable this for IPv4 only environments
        /* listen-on-v6 port 53 { ::1; }; */
        directory       "/var/named";
        dump-file       "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
        allow-query     { allowed_networks; };
        recursion yes;

        // Use this to allow slave DNS servers to get the transfers
        /* allow-transfer { allowed_slaves; } */

        managed-keys-directory "/var/named/dynamic";

logging {
        channel default_debug {
                file "data/";
                severity dynamic;

zone "." IN {
        type hint;
        file "";

include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

Verify that the DNS servers you want to cache from are correctly set in /etc/resolv.conf (usual DNS nameserver fields configuration).

Then test the configuration and start the service. Be careful, at first start, the service will generate the rndc key which can really take a long time.

service named configtest
service named start

2. Client-side configuration

On the client, make your /etc/resolv.conf include the nameserver either by using network-manager or directly editing the file.

If you don’t use network-manager and you want the configuration to persist between reboots, don’t forget to change the DNS1 and DNS2 entries in /etc/sysconfig/network.

If you have to troubleshoot, install the bind-utils package and use the host, nslookup and dig commands (dig @my_caching_dns_server