How to set up "Two in one DNS server or DNS split-Horizon" (2)

In tutorial(1) we showed you how to configure a DNS split-horizon master server and also how to create zone (reverse zone) files. It is a good idea to have a slave DNS server. A slave DNS server gets its zone data using a zone transfer operation from master (usually), and it will respond as authoritative for those zones for which it is defined to be a 'slave' and for which it has a currently valid zone configuration.

Note that it is impossible to determine from a query result that it came from a zone master or slave.

In Bind9, slave status is defined by "type slave" in zone declaration section in named.conf file.

To configure a slave dns server:
Assume we will use slave.test.com - Internal IP address is (10.168.1.100)
1. Install bind service on slave.test.com

# yum install bind

2. Edit your /etc/named.conf file:

//
// 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 {
        directory       "/var/named";
};

zone "test.com" {
        type slave;
        masters {10.168.1.0;};
        file "slaves/db.test.com";
};

zone "1.168.10.in-addr.arpa" IN {
        type slave;
        masters {10.168.1.0;};
        file "slaves/1.168.10.in-addr.arpa";
};

In options, we are using bind's chroot features so all our necessary files will be stored in chroot directory (/var/named).

3. In your master DNS server, add the following into /etc/named.conf file:

acl slaves {
    10.168.1.100;  // XName
};

and for all the zone definition, add
allow-transfer { slaves; };

for example:

zone "1.168.10.in-addr.arpa" IN {
        type master;
        file "/etc/named/internals/1.168.10.in-addr.arpa";
        allow-transfer { slaves; };
};

4. Restart named service on DNS master.

# service named restart

5. Now start the named service. It should be start without any error.

6. In /var/named/slaves directory, you can see now there are newly generated files "db.test.com" and "1.168.10.in-addr.arpa".