As Slave/Secondary DNS Server is a exact copy of the master DNS server, In case the Master/Primary Server becomes unavailable or server got down due to some reason, till the server gets up the Secondary DNS Server will accept the query without effecting the end user work.Before configure the Slave/Secondary DNS Server we need to do some changes in our all Master/Primary DNS Server configuration files i.e.IN A 192.168.1.100 ; mail exchanger record (MX record) IN MX 5 ns1.; host and canonical name records mail IN CNAME ns1.Everyone in the world has a first name and a last, or family, name.The same thing is true in the DNS world: A family of Web sites can be loosely described a domain.article before read this article so that you can properly understand the whole topic.Slave/Secondary DNS Server is a server which is like a Load balancer or Backup server of Master/Primary DNS Server, Its takes all DNS query Records/Zones from Master Server.
Using fully qualified domain names (FQDNs), instead of IP addresses, to specify network addresses eases the configuration of services and applications, and increases the maintainability of configuration files.
Setting up your own DNS for your private network is a great way to improve the management of your servers.
In this tutorial, we will go over how to set up an internal DNS server, using the BIND name server software (BIND9) on Ubuntu 14.04, that can be used by your Virtual Private Servers (VPS) to resolve private host names and private IP addresses.
1) Make sure your Bind 9 is installed and working properly.
There are several resources on the Internet that can help you install it depending on your platform.