Configure linux dns slave server step by step guide example and implementation

The DNS ( Domain Name System ) is a distributed system, used for transalate domain names to IP and vice a versa.
For example when we type domain name in browser url like “http://www.linuxadmin.net”, Our computer sends a request to DNS and get an ip address of domain. Below steps are to configure dns server on centos 6 or RHEL 6 systems.

Network Setup used in Tutorial:

1. DNS Server IP: 10.3.150.14
2. DNS Server Name: ns1.linuxadmin.net, ns2.linuxadmin.net
3. Domain Name : demolinuxadmin.net
4. Domain IP to point: 10.3.150.15

Step 1: Install required rpms using yum.

# yum install bind bind-chroot caching-nameserver

Step 2: Edit DNS configuration file.

There are two types of configuration files in DNS.

>> One is main dns configuration files named “named.conf”.
>> Another type of configuration file are called zone file. Which is individually created for all domains. named.conf keeps an entry for all zone files.

2.1 Configure named.conf using below configuration

# vim /var/named/chroot/etc/named.conf

Content of named.conf:

// /var/named/chroot/etc/named.conf
options {
        listen-on port 53 { 127.0.0.1; 192.168.1.0/24; };
        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     { localhost; 192.168.1.0/24; };
        recursion yes;

        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";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
        type hint;
        file "named.ca";
};

zone "demolinuxadmin.net" IN {
        type master;
        file "/var/named/demolinuxadmin.net.db";
};

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

2.2 Create a zone file for you domain “demolinuxadmin.net”

# vim /var/named/chroot/var/named/demolinuxadmin.net.db

Content of zone file:

; Zone file for demolinuxadmin.net
$TTL 14400
@      86400    IN      SOA     ns1.linuxadmin.net. webmaster.linuxadmin.net. (
                3013040200      ; serial, todays date+todays
                86400           ; refresh, seconds
                7200            ; retry, seconds
                3600000         ; expire, seconds
                86400 )         ; minimum, seconds

demolinuxadmin.net. 86400 IN NS ns1.linuxadmin.net.
demolinuxadmin.net. 86400 IN NS ns2.linuxadmin.net.
demolinuxadmin.net. IN A 10.3.150.15
demolinuxadmin.net. IN MX 0 demolinuxadmin.net.
mail IN CNAME demolinuxadmin.net.
www IN CNAME demolinuxadmin.net.

2.3 Add more domains in dns server.
To add more domains in dns, create zone files individually for all domain as above. After that add any entry for all zones in named.conf like below. Change demolinuxadmin.net with your domain name.

zone "demolinuxadmin.net" IN {
        type master;
        file "/var/named/demolinuxadmin.net.db";
};

Step 3: Start named service.

Start named (bind) service using below command.

# /etc/init.d/named restart

Enable auto start on system boot.

# chkconfig named on

Step 4: Finally test your DNS setup.

Send query to your dns server directly using below command.
Syntax: nslookup < domainname > < dns server name/ip >

# nslookup demolinuxadmin.net 10.3.150.14

Sample Output:

Server:         10.3.150.14
Address:        10.3.150.14#53

Name:   demolinuxadmin.net
Address: 10.3.150.15

Above output is showing that dns server has successfully resolved domain demolinuxadmin.net.