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How to install BIND/NAMED on CentOS 6
This article will show you how to setup and configure the BIND DNS Server.
Before we begin, it is recommended you have at least two cloud servers to run your nameservers. Two nameservers are suggested to assure your primary and secondary servers are redundant in case of failure.
It is worth noting that if you are managing a large number of domains this may not be the most viable solution, as you will need to manually add domains on both the master and slave nameservers. With that said, running your own nameservers is a great way to have more direct control over your hosting infrastructure, and assert full control over your DNS records.
As with any new server, it's always important to ensure your system is up to date. You can verify this by checking for updates using yum as follows:
yum update -y
Initial BIND Installation To begin, we will need to install the BIND and BIND Utilities packages using yum.
yum install bind bind-utils -y
Next, we'll open the BIND (named) configuration file and make several modifications.
nano -w /etc/named.conf
Your "options" section should appear as follows, replacing 2.2.2.2 with the IP of your second vps.
options {
        #listen-on port 53 { 127.0.0.1; };
        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 { any; };
        allow-transfer     { localhost; 2.2.2.2; };
        recursion no;

        dnssec-enable yes;
        dnssec-validation yes;
        dnssec-lookaside auto;

        /* Path to ISC DLV key */
        bindkeys-file "/etc/named.iscdlv.key";

        managed-keys-directory "/var/named/dynamic";
};
Above, listen-on must be commented to listen on all available interfaces. Recursion should be turned off to prevent your server from being abused in "reflection" DDoS attacks. The allow-transfer directive whitelists transfers to your secondary vps's IP. Furthermore, we have changed the allow-query directive to "any" in order to allow users proper access to hosted zones. Next, we'll want to add a new zone for our first domain, you should add the following to your named.conf below the existing zones.
        zone "mydomain.com" IN {
                type master;
                file "mydomain.com.zone";
                allow-update { none; };
        };		
		
After saving named.conf with the changes above, we're ready to create our first zone file. Configure BIND Zones Firstly, we'll need to open the zone file, using the name you specified in the configuration above. (Ex: mydomain.com.zone)
nano -w /var/named/mydomain.com.zone
We'll add the following contents to our newly created file. You should replace the applicable information with your own, where 1.1.1.1 is the IP of your first vps, 2.2.2.2 is the IP of your second vps and 3.3.3.3 is the IP you wish to point the domain itself to, such as a vps running a webserver. You are free to add additional entries in the same format.
$TTL 86400
@   IN  SOA     ns1.mydomain.com. root.mydomain.com. (
        2013042201  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
; Specify our two nameservers
        IN    NS        ns1.mydomain.com.
        IN    NS        ns2.mydomain.com.
; Resolve nameserver hostnames to IP, replace with your two vps IP addresses.
ns1        IN    A        1.1.1.1
ns2        IN    A        2.2.2.2

; Define hostname -> IP pairs which you wish to resolve
@        IN    A        3.3.3.3
www        IN    A        3.3.3.3
We can now start named for the first time. This may take several minutes while named generates the rndc.key file, which only occurs on first execution.
service named restart
Once named has started successfully, we'll want to ensure that it is enabled as a startup service, by running the following:
chkconfig named on
By now, we should have a fully operational primary nameserver. You can verify that BIND is working correctly by running the following command, replacing 1.1.1.1 with the IP of your first vps.
dig @1.1.1.1 mydomain.com
If you recieve a response which includes an answer and authority section, your nameserver has been configured correctly. Slave Nameserver Configuration With our primary nameserver configured, we'll now setup a slave nameserver on our second cloud server. As always, please assure your system is up to date by checking for updates with yum as follows:
yum update -y
We can start by installing BIND (and related utilities) on the second vps, in the same manner as the first:
yum install bind bind-utils -y
We'll proceed by opening named.conf and making the same changes we made previously, ommitting the "allow transfer" line. This directive is unnecessary as we will only be transfering records from our primary nameserver.
nano -w /etc/named.conf
options {
        #listen-on port 53 { 127.0.0.1; };
        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 { any; };
        recursion no;

        dnssec-enable yes;
        dnssec-validation yes;
        dnssec-lookaside auto;

        /* Path to ISC DLV key */
        bindkeys-file "/etc/named.iscdlv.key";

        managed-keys-directory "/var/named/dynamic";
};
We will add the zone we configured on the first vps, this time changing the "type" directive to slave, instead of master. You should replace "1.1.1.1" with your first vps's IP address.
zone "mydomain.com" IN {
    type slave;
    masters { 1.1.1.1; };
    file "mydomain.com.zone";
};
After configuring our slave zone, we'll start named. Again this may take several minutes while our rndc.key file is initially generated.
service named start
As with the first cloud server, we want to assure named is set to run at startup with the following:
chkconfig named on
Your slave nameserver should now be up and running. You can verify that it is fully operational by using dig again, replacing 2.2.2.2 with the IP of your second vps.
dig @2.2.2.2 mydomain.com
After any changes you make to the master zone files, you will need to instruct BIND to reload. Remember, you must also increment the "serial" directive to ensure synchronicity between the master and slave. To reload the zone files, we need to run the following command on the master nameserver, followed by the slave:
rndc reload
Enjoy!
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