Setting up Master Slave DNS server

The DNS ( Domain Name System ) is a distributed system, used for translate domain names to IP and vice a versa

Network Scenario for this Setup
Master DNS Server IP: 10.10.10.20 ( ns1.example.net )
Slave  DNS Server IP: 10.10.11.243 ( ns2.example.net )
Domain Name : demoexample.net   ( For Testing Purpose )
Domain IP   : 10.10.10.100  ( For Testing Purpose )
Install Required RPMS ( at Master and Slave Both )

Install bind packages at both Master and Slave dns servers using following commands.

# yum install bind bind-chroot
Setup Master (NS1) DNS Server

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.
Configure named.conf using below configuration
# vim /var/named/chroot/etc/named.conf

Content of named.conf:

// /var/named/chroot/etc/named.conf
acl internals {
    127.0.0.0/8;
    10.10.10.0/24;
    10.10.11.0/24;
   115.254.78.93;
};

acl slaves {
    10.10.11.243/32;
    97.74.243.55/32;
    10.10.10.0/24;
};

acl trusted {
        10.10.11.240/28;
        10.10.10.0/24;
};

options {
        listen-on port 53 { 127.0.0.1; any; };
        listen-on-v6 { any; };
#       version "Please go Ahead";
        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";
#        query-source    port 53;
#        query-source-v6 port 53;
        allow-query     { any; };
        allow-recursion {
                        slaves;
                        trusted;
                        internals;
                         };
        allow-transfer { slaves; };
};

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

logging {
   channel default_syslog { syslog local2; severity notice; };
   category "default" { "debug"; };
   category "general" { "debug"; };
   category "database" { "debug"; };
   category "security" { "debug"; };
   category "config" { "debug"; };
   category "resolver" { "debug"; };
   category "xfer-in" { "debug"; };
   category "xfer-out" { "debug"; };
   category "notify" { "debug"; };
   category "client" { "debug"; };
   category "unmatched" { "debug"; };
   category "network" { "debug"; };
   category "update" { "debug"; };
   category "queries" { "debug"; };
   category "dispatch" { "debug"; };
   category "dnssec" { "debug"; };
   category lame-servers {null; };
   category edns-disabled { null; };
   channel "debug" {
     file "/var/log/named/named.log" versions 2 size 1024m;
     print-time yes;
     print-category yes;
   };
};



include "/etc/rndc.key";
controls {
        inet 127.0.0.1 port 953 allow { localhost; };
       };

view localhost_resolver {
        match-clients      { internals; };
        match-destinations { localnets; };
#        recursion yes;
        include "/etc/named.rfc1912.zones";
        include "/var/named/named.zones";
        include "/var/named/named_new.zones";
};
view "external" {
        match-clients      { any; };
        match-destinations { any; };
#        recursion no;

        include "/var/named/named.zones";
        include "/var/named/named_new.zones";
};
# vim /var/named/named.zones

Content of named.zones:

zone "example.net" IN {
        type master;
        file "example.net.zone";
        allow-transfer {
                10.10.11.243;
        };
};
zone "nethost.com" IN {
        type master;
        file "nethost.com.zone";
        allow-transfer {
                10.10.11.243;
        };
};
zone "testreflexologydayspa.com" IN {
        type master;
        file "testreflexologydayspa.com.zone";
        allow-transfer {
                10.10.11.243;
        };
};
zone "nethost.net" IN {
        type master;
        file "nethost.net.zone";
        allow-transfer {
                10.10.11.243;
        };
};
# vim /var/named/named_new.zones

Content of named_new.zones:

zone "sahana.on.com"{
       type master;
       file "s/p-sahana.on.com";
        also-notify { 64.68.200.91; };
       allow-transfer {
       10.10.11.243;
        64.68.200.91;
        72.52.2.1;
        64.68.196.10;
        64.68.192.210;
       };
};
zone "oahanacolleges.com"{
       type master;
       file "o/p-oahanacolleges.com";
        also-notify { 64.68.200.91; };
       allow-transfer {
        64.68.200.91;
       10.10.11.243;
        72.52.2.1;
        64.68.196.10;
        64.68.192.210;
       };
};
zone "1101baybay.ca"{
       type master;
       file "1/p-1101baybay.ca";
       allow-transfer {
       10.10.11.243;
       };
};
Create a zone file for your domain “example.net”
# vim /var/named/example.net

Content of zone file:

$ORIGIN .
$TTL 600        ; 10 minutes
example.net     IN SOA  sys.example.net. root.sys.example.net. (
                                2014021800 ; serial
                                7200       ; refresh (2 hours)
                                3600       ; retry (1 hour)
                                43200     ; expire (1 week)
                                3600       ; minimum (1 hour)
                                )
                        NS      ns1.example.net.
                        NS      ns2.example.net.
                        A       10.10.10.32
                        MX      0 example-net.mail.eo.outlook.com.
                        TXT     "v=spf1 include:outlook.com ~all"
                        SRV     100 1 5061 sipfed.online.lync.com.
$ORIGIN example.net.
adminfs                 A       10.10.11.29
autodiscover            CNAME   autodiscover.outlook.com.
home                    A       10.10.10.95
ns1                     A       10.10.10.20
ns2                     A       10.10.11.243
ns3                     A       10.10.11.243
webmail                        IN        A         10.10.10.64
*                              IN        A         10.10.10.64
Create a zone file for your reverse domain “10.10.10.in-addr.arpa.zone”
# vim /var/named/10.10.10.in-addr.arpa.zone

Content of zone file:

$ORIGIN .
$TTL 600        ; 10 minutes
10.10.10.in-addr.arpa IN SOA  ns1.example.net. root.example.net. (
                                2014032001 ; serial
                                7200       ; refresh (2 hours)
                                3600       ; retry (1 hour)
                                43200     ; expire (1 week)
                                3600       ; minimum (1 hour)
                                )
                        NS      ns1.example.net.
                        NS      ns2.example.net.
$ORIGIN 10.10.10.in-addr.arpa.
100                     PTR     cpanel.midinet.com.
120                     PTR     winpl.midinet.com.
150                     PTR     urban.ca.
20                      PTR     ns1.example.net.
85                      PTR     ratherlaugh.com.
86                      PTR     statusopenged.com.
87                      PTR     open.statusopenged.com.
88                      PTR     offresgetsmain.net.
89                      PTR     stat.offresgetsmain.net.
227                     PTR     devanorth.com.
84                      PTR     wiki.eausergroup.org.
55                      PTR     equipmentscheduling.com.
Start named service

Startnamed(bind) service using following command and setup auto start on system boot.

# /etc/init.d/named restart
# chkconfig named on
Setup Slave (NS2) DNS Server

At slave dns server you need to updatenamed.conf file only. All zone files will automatically synced from master dns server. Any changes done on Master will reflect on slave after a specified time interval.

Configure named.conf using below configuration
# vim /var/named/chroot/etc/named.conf

Content of named.conf

// /var/named/chroot/etc/named.conf
acl trusted {
        10.10.11.240/28;
        10.10.10.0/24;
        10.10.11.0/24;
};


options {
        listen-on port 53 { 127.0.0.1; any; };
        version "Please go Ahead";
        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";
#        query-source    port 53;
#        query-source-v6 port 53;
        allow-query     { any; };
        allow-transfer { none; };
        allow-recursion { trusted;};
        allow-notify {trusted;};

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


logging {
   channel default_syslog { syslog local2; severity notice; };
   category "default" { "debug"; };
   category "general" { "debug"; };
   category "database" { "debug"; };
   category "security" { "debug"; };
   category "config" { "debug"; };
   category "resolver" { "debug"; };
   category "xfer-in" { "debug"; };
   category "xfer-out" { "debug"; };
   category "notify" { "debug"; };
   category "client" { "debug"; };
   category "unmatched" { "debug"; };
   category "network" { "debug"; };
   category "update" { "debug"; };
   category "queries" { "debug"; };
   category "dispatch" { "debug"; };
   category "dnssec" { "debug"; };
   category lame-servers {null; };
#   category edns-disabled { null; };
   channel "debug" {
     file "/var/log/named/named.log" versions 2 size 150m;
     print-time yes;
     print-category yes;
   };
};

include "/etc/rndc.key";
controls {
        inet 127.0.0.1 port 953 allow { localhost; };
       };
view localhost_resolver {
        match-clients      { localnets; };
        match-destinations { localhost; };
#        recursion yes;
        include "/etc/named.rfc1912.zones";
        include "/var/named/named.zones";
        include "/var/named/named_new.zones";
};
view "external" {
        match-clients      { any; };
        match-destinations { any; };
        include "/var/named/named.zones";
        include "/var/named/named_new.zones";
};
# vim /var/named/named.zones
zone "example.net" IN {
        type slave;
        masters { 10.10.10.20; };
        file "example.net.zone";
};
zone "nethost.com" IN {
        type slave;
        masters { 10.10.10.20; };
        file "nethost.com.zone";
};
zone "reflexologydayspa.com" IN {
        type slave;
        masters { 10.10.10.20; };
        file "reflexologydayspa.com.zone";
};
zone "nethost.net" IN {
        type slave;
        masters { 10.10.10.20; };
        file "nethost.net.zone";
};
zone "westmountroutes.com" IN {
        type slave;
        masters { 10.10.10.20; };
        file "westmountroutes.com.zone";
};
zone "siteinmotionhosting.com" IN {
        type slave;
        masters { 10.10.10.20; };
        file "siteinmotionhosting.com.zone";
};
# vim /var/named/named_new.zones
zone "iaaos.ca"{
       type slave;
       masters { 10.10.10.20; } ;
       file "i/s-iaaos.ca";
};
zone "saco.ca"{
       type slave;
       masters { 10.10.10.20; } ;
       file "o/s-saco.ca";
};
zone "schooldelontario.ca"{
       type slave;
       masters { 10.10.10.20; } ;
       file "c/s-schooldelontario.ca";
};
zone "saco.on.ca"{
       type slave;
       masters { 10.10.10.20; } ;
       file "s/s-saco.on.ca";
};
zone "ontarioschool.ca"{
       type slave;
       masters { 10.10.10.20; } ;
       file "o/s-ontarioschool.ca";
};
zone "1101bay.ca"{
       type slave;
       masters { 10.10.10.20; } ;
       file "1/s-1101bay.ca";
};
zone "1101bay.com"{
       type slave;
       masters { 10.10.10.20; } ;
       file "1/s-1101bay.com";
};
# vim /var/named/example.net.zone
$ORIGIN .
$TTL 600        ; 10 minutes
example.net     IN SOA  ns1.example.net. root.ns1.example.net. (
                                2014021800 ; serial
                                7200       ; refresh (2 hours)
                                3600       ; retry (1 hour)
                                43200     ; expire (1 week)
                                3600       ; minimum (1 hour)
                                )
                        NS      ns1.example.net.
                        NS      ns2.example.net.
                        A       10.10.10.32
                        MX      0 example-net.mail.eo.outlook.com.
                        TXT     "v=spf1 include:outlook.com ~all"
                        SRV     100 1 5061 sipfed.online.lync.com.
$ORIGIN example.net.
adminfs                 A       10.10.11.29
autodiscover            CNAME   autodiscover.outlook.com.
home                    A       10.10.10.95
ns1                     A       10.10.10.20
ns2                     A       10.10.11.243
ns3                     A       10.10.11.243
webmail                 A       10.10.10.64
*                       A       10.10.10.64
# vim /var/named/10.10.10.in-addr.arpa.zone
$ORIGIN .
$TTL 600        ; 10 minutes
10.10.10.in-addr.arpa IN SOA  ns1.example.net. root.example.net. (
                                2014032001 ; serial
                                7200       ; refresh (2 hours)
                                3600       ; retry (1 hour)
                                43200     ; expire (1 week)
                                3600       ; minimum (1 hour)
                                )
                        NS      ns1.example.net.
                        NS      ns2.example.net.
$ORIGIN 10.10.10.in-addr.arpa.
100                     PTR     cpanel.midinet.com.
120                     PTR     winpl.midinet.com.
150                     PTR     urban.ca.
20                      PTR     ns1.example.net.
85                      PTR     ratherlaugh.com.
86                      PTR     statusopenged.com.
87                      PTR     open.statusopenged.com.
88                      PTR     offresgetsmain.net.
89                      PTR     stat.offresgetsmain.net.
227                     PTR     devanorth.com.
84                      PTR     wiki.eausergroup.org.
55                      PTR     equipmentscheduling.com.
Start named Service

Startnamed(bind) service using below command.

# /etc/init.d/named restart
# chkconfig named on

After restartingnamedservice, Check zone files on slave dns server at /var/named/chroot/var/named/slaves/.

Step 4: Finally Test Your DNS Setup

Query to your Master and Slave DNS Server directly using following commands, You will get the same resonse from both servers.
Syntax: nslookup <domainname.com> <dns server name/ip>

Query to Master DNS Server:

# nslookup demoexample.net 10.10.10.20

Server:         10.10.10.20
Address:        10.10.10.20#53

Name:   demoexample.net
Address: 10.10.10.100

Query to Slave DNS Server:

# nslookup demoexample.net 10.10.11.243

Server:         10.10.11.243
Address:        10.10.11.243#53

Name:   demoexample.net
Address: 10.10.10.100

Above outputs is showing that dns server has successfully resolved domain demoexample.net from master and slave dns servers.

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