Scenario
Primary(Master) DNS Server Details:
Operating System: CentOS 6.5 server
Hostname: masterdns.unixmen.local
IP Address: 192.168.1.100/24
Secondary(Slave) DNS Server Details:
Operating System: CentOS 6.5 server
Hostname: secondarydns.unixmen.local
IP Address: 192.168.1.101/24
Client Details:
Operating System: CentOS 6.5 Desktop
Hostname: Client.unixmen.local
IP Address: 192.168.1.102/24
Setup Primary(Master) DNS Server
[root@masterdns ~]# yum install bind* -y
1. Configure DNS Server
Add the lines as shown below in ‘/etc/named.conf’ file
[root@masterdns ~]# vi /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 { 127.0.0.1; 192.168.1.100; }; ### Master DNS IP ###
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; }; ### IP Range ###
allow-transfer{ localhost; 192.168.1.101; }; ### Slave DNS IP ###
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”unixmen.local” IN {
type master;
file “forward.unixmen”;
allow-update { none; };
};
zone”1.168.192.in-addr.arpa” IN {
type master;
file “reverse.unixmen”;
allow-update { none; };
};
include “/etc/named.rfc1912.zones”;
include “/etc/named.root.key”;
2. Create Zone files
Create forward and reverse zone files which we mentioned in the ‘/etc/named.conf’ file.
2.1 Create Forward Zone
Create forward.unixmen file in the ‘/var/named’ directory.
[root@masterdns ~]# vi /var/named/forward.unixmen
$TTL 86400
@ IN SOA masterdns.unixmen.local. root.unixmen.local. (
2011071001 ;Serial
3600 ;Refresh
1800 ;Retry
604800 ;Expire
86400 ;Minimum TTL
)
@ IN NS masterdns.unixmen.local.
@ IN NS secondarydns.unixmen.local.
@ IN A 192.168.1.100
@ IN A 192.168.1.101
@ IN A 192.168.1.102
masterdns IN A 192.168.1.100
secondarydns IN A 192.168.1.101
client IN A 192.168.1.102
2.2 Create Reverse Zone
Create reverse.unixmen file in the ‘/var/named’ directory.
[root@masterdns ~]# vi /var/named/reverse.unixmen
$TTL 86400
@ IN SOA masterdns.unixmen.local. root.unixmen.local. (
2011071001 ;Serial
3600 ;Refresh
1800 ;Retry
604800 ;Expire
86400 ;Minimum TTL
)
@ IN NS masterdns.unixmen.local.
@ IN NS secondarydns.unixmen.local.
@ IN PTR unixmen.local.
masterdns IN A 192.168.1.100
secondarydns IN A 192.168.1.101
client IN A 192.168.1.102
100 IN PTR masterdns.unixmen.local.
101 IN PTR secondarydns.unixmen.local.
102 IN PTR client.unixmen.local.
3. Start the DNS service
[root@masterdns ~]# service named start
Starting named: [ OK ]
[root@masterdns ~]# chkconfig named on
4. Adjust iptables to allow DNS server from outside of the network
Add the lines as shown below in ‘/etc/sysconfig/iptables’ file.
[root@masterdns ~]# vi /etc/sysconfig/iptables
# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -p udp -m state –state NEW –dport 53 -j ACCEPT
-A INPUT -p tcp -m state –state NEW –dport 53 -j ACCEPT
-A INPUT -m state –state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state –state NEW -m tcp -p tcp –dport 22 -j ACCEPT
-A INPUT -j REJECT –reject-with icmp-host-prohibited
-A FORWARD -j REJECT –reject-with icmp-host-prohibited
COMMIT
5. Restart iptables
[root@masterdns ~]# service iptables restart
iptables: Flushing firewall rules: [ OK ]
iptables: Setting chains to policy ACCEPT: filter [ OK ]
iptables: Unloading modules: [ OK ]
iptables: Applying firewall rules: [ OK ]
6. Test DNS configuration and zone files for any syntax errors
[root@masterdns ~]# named-checkconf /etc/named.conf
[root@masterdns ~]# named-checkzone unixmen.local /var/named/forward.unixmen
zone unixmen.local/IN: loaded serial 2011071001
OK
[root@masterdns ~]# named-checkzone unixmen.local /var/named/reverse.unixmen
zone unixmen.local/IN: loaded serial 2011071001
OK
7. Test DNS Server
[root@masterdns ~]# dig masterdns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49834
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;masterdns.unixmen.local.INA
;; ANSWER SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; AUTHORITY SECTION:
unixmen.local.86400INNSsecondarydns.unixmen.local.
unixmen.local.86400INNSmasterdns.unixmen.local.
;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 6 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar 7 13:07:56 2013
;; MSG SIZE rcvd: 114
[root@masterdns ~]# nslookup unixmen.local
Server:192.168.1.100
Address:192.168.1.100#53
Name:unixmen.local
Address: 192.168.1.102
Name:unixmen.local
Address: 192.168.1.100
Name:unixmen.local
Address: 192.168.1.101
Now the Primary DNS server is ready to use.
Setup Secondary(Slave) DNS Server
[root@secondarydns ~]# yum install bind* -y
1. Configure Slave DNS Server
Open the main configuration file ‘/etc/named.conf’ and add the lines as shown below.
[root@secondarydns ~]# vi /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 { 127.0.0.1; 192.168.1.101; };
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”unixmen.local” IN {
type slave;
file “slaves/unixmen.fwd”;
masters { 192.168.1.100; };
};
zone”1.168.192.in-addr.arpa” IN {
type slave;
file “slaves/unixmen.rev”;
masters { 192.168.1.100; };
};
include “/etc/named.rfc1912.zones”;
include “/etc/named.root.key”;
2. Start the DNS Service
[root@secondarydns ~]# service named start
Generating /etc/rndc.key: [ OK ]
Starting named: [ OK ]
[root@secondarydns ~]# chkconfig named on
Now the forward and reverse zones are automatically replicated from Master DNS server to ‘/var/named/slaves/’in Secondary DNS server.
[root@secondarydns ~]# ls /var/named/slaves/
unixmen.fwd unixmen.rev
[root@secondarydns ~]# cat /var/named/slaves/unixmen.fwd
$ORIGIN .
$TTL 86400; 1 day
unixmen.localIN SOAmasterdns.unixmen.local. root.unixmen.local. (
2011071001 ; serial
3600 ; refresh (1 hour)
1800 ; retry (30 minutes)
604800 ; expire (1 week)
86400 ; minimum (1 day)
)
NS masterdns.unixmen.local.
NS secondarydns.unixmen.local.
A192.168.1.100
A192.168.1.101
A192.168.1.102
$ORIGIN unixmen.local.
clientA192.168.1.102
masterdnsA192.168.1.100
secondarydnsA192.168.1.101
[root@secondarydns ~]# cat /var/named/slaves/unixmen.rev
$ORIGIN .
$TTL 86400; 1 day
1.168.192.in-addr.arpaIN SOAmasterdns.unixmen.local. root.unixmen.local. (
2011071001 ; serial
3600 ; refresh (1 hour)
1800 ; retry (30 minutes)
604800 ; expire (1 week)
86400 ; minimum (1 day)
)
NS masterdns.unixmen.local.
NS secondarydns.unixmen.local.
PTRunixmen.local.
$ORIGIN 1.168.192.in-addr.arpa.
100PTRmasterdns.unixmen.local.
101PTRsecondarydns.unixmen.local.
102PTRclient.unixmen.local.
clientA192.168.1.102
masterdnsA192.168.1.100
secondarydnsA192.168.1.101
3. Add the DNS Server details to all systems
[root@secondarydns ~]# vi /etc/resolv.conf
# Generated by NetworkManager
search ostechnix.com
nameserver 192.168.1.100
nameserver 192.168.1.101
nameserver 8.8.8.8
4. Test DNS Server
[root@secondarydns ~]# dig masterdns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21487
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;masterdns.unixmen.local.INA
;; ANSWER SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 15 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar 7 13:27:57 2013
;; MSG SIZE rcvd: 114
[root@secondarydns ~]# dig secondarydns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> secondarydns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20958
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;secondarydns.unixmen.local.INA
;; ANSWER SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; Query time: 4 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar 7 13:31:53 2013
;; MSG SIZE rcvd: 114
[root@secondarydns ~]# nslookup unixmen.local
Server:192.168.1.100
Address:192.168.1.100#53
Name:unixmen.local
Address: 192.168.1.101
Name:unixmen.local
Address: 192.168.1.102
Name:unixmen.local
Address: 192.168.1.100
Client Side Configuration
Add the DNS server details in ‘/etc/resolv.conf’ file in all client systems
[root@client unixmen]# vi /etc/resolv.conf
# Generated by NetworkManager
search unixmen.local
nameserver 192.168.1.100
nameserver 192.168.1.101
nameserver 8.8.8.8
Test DNS Server
[root@client unixmen]# dig masterdns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19496
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;masterdns.unixmen.local.INA
;; ANSWER SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 30 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar 7 13:47:55 2013
;; MSG SIZE rcvd: 114
[root@client unixmen]# dig secondarydns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> secondarydns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14852
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;secondarydns.unixmen.local.INA
;; ANSWER SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; AUTHORITY SECTION:
unixmen.local.86400INNSsecondarydns.unixmen.local.
unixmen.local.86400INNSmasterdns.unixmen.local.
;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; Query time: 8 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar 7 13:48:38 2013
;; MSG SIZE rcvd: 114
[root@client unixmen]# dig client.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> client.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14604
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
;; QUESTION SECTION:
;client.unixmen.local.INA
;; ANSWER SECTION:
client.unixmen.local.86400INA192.168.1.102
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 5 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar 7 13:49:11 2013
;; MSG SIZE rcvd: 137
[root@client unixmen]# nslookup unixmen.local
Server:192.168.1.100
Address:192.168.1.100#53
Name:unixmen.local
Address: 192.168.1.102
Name:unixmen.local
Address: 192.168.1.100
Name:unixmen.local
Address: 192.168.1.101
My name is Rayhan and I’m an IT professional with over 10 years of experience in the field. I’m passionate about all things tech, and I love helping people solve their IT problems. In my free time, I enjoy tinkering with new gadgets and software, and I’m always on the lookout for the latest tech trends. I believe that technology has the power to make our lives easier and more enjoyable, and I’m excited to be a part of this ever-evolving field. Thank you for taking the time to visit my page.