DNS

DNS helps to resolve domain name to ip address and ip address to domain name . In this post we can see how to configure DNS server on centos 6.

Install dns server in centos 6 :

Just follow the step by step instruction to setup dns server on centos 6 .
You can also refer the below posts for Centos OS installation and network configuration

» Centos 6 installation step by step screenshots

» How to setup network in centos 6

Step 1 » Install bind packages by issuing the below command.
[root@localhost ~]# yum install bind*

Step 2 » Assign static IP address.
[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE="eth0"
HWADDR="00:0C:29:0D:FB:E2"
NM_CONTROLLED="yes"
ONBOOT="yes"
BOOTPROTO="static"
IPADDR=172.16.28.5
NETMASK=255.255.255.0
GATEWAY=172.16.28.1

Step 3 » Assign fully qualified domain name for the server ( Ex: dns1.krizna.com )
[root@localhost ~]# vim /etc/sysconfig/network

NETWORKING=yes
HOSTNAME=dns1.krizna.com

Step 4 » Add a host entry in the host file .
[root@localhost ~]# vim /etc/hosts

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
172.16.28.5   dns1.krizna.com

Step 5 » Add server ip to the resolve.conf file.
[root@localhost ~]# vim /etc/resolv.conf

search krizna.com
nameserver 172.16.28.5

Just We completed pre requirements for DNS server . Lets start main configuration
Step 6 » Open /etc/named.conf file and Edit the following line Nos 11,12 and 17 like below
[root@localhost ~]# vim /etc/named.conf


//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
options {
        listen-on port 53 { 172.16.28.5; };    ## replace with your IP 
Step 6 »  Now open /etc/named.rfc1912.zones file and edit the following line nos 13,14,31 and 32
[root@localhost ~]# vim /etc/named.rfc1912.zones
 
// named.rfc1912.zones:
//
// Provided by Red Hat caching-nameserver package
//
// ISC BIND named zone configuration for zones recommended by
// RFC 1912 section 4.1 : localhost TLDs and address zones
// and http://www.ietf.org/internet-drafts/draft-ietf-dnsop-default-local-zones-02.txt
// (c)2007 R W Franks
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//

zone "krizna.com" IN {                 ## Your domain name       
Step 7 »  Now create forward and reverse zone files like below
[root@localhost ~]# cp /var/named/named.localhost /var/named/forward.zone

[root@localhost ~]# cp /var/named/named.loopback /var/named/reverse.zone

Step 8 »  Open the forward zone file and replace with your hostname like below
[root@localhost ~]# vim /var/named/forward.zone
 
$TTL 1D
@ IN SOA dns1.krizna.com. root.dns1.krizna.com. (       
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        IN NS   dns1.krizna.com.                      
dns1    IN A    172.16.28.5
 
Step 9 »  Now open the reverse zone file and replace like below .
[root@localhost ~]# vim /var/named/reverse.zone 
 
$TTL 1D
@ IN SOA dns1.krizna.com. root.dns1.krizna.com. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        IN NS      dns1.krizna.com.
5       IN PTR     dns1.krizna.com.
 
Step 10 »  Now set group permissions for the files


[root@localhost ~]# chgrp named /var/named/forward.zone

[root@localhost ~]# chgrp named /var/named/reverse.zone

Step 11 »  That's it , now start the service by typing the below command
 
[root@localhost ~]# service named start
Generating /etc/rndc.key:                                  [  OK  ]
Starting named:                                            [  OK  ]
 
Step 12 »  Issue the below command to start service on bootup and  Reboot the server
[root@localhost ~]# chkconfig --levels 235 named on 
 
Step 13 »  After rebooting .Just issue the below commands to test your dns server
[root@dns1 ~]# dig
 
; > DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 >
;; global options: +cmd
;; Got answer:
;; ->>HEADER
[root@dns1 ~]# nslookup dns1.krizna.com
Server:  172.16.28.5
Address: 172.16.28.5#53

Name: dns1.krizna.com
Address: 172.27.16.5
 
[root@dns1 ~]# nslookup 172.16.28.5
Server:  172.16.28.5
Address: 172.16.28.5#53

5.28.16.172.in-addr.arpa name = dns1.krizna.com.

[root@dns1 ~]# 
 
All the best