Disable Open DNS Recursion

The DNS recursion mean the DNS will not query any other DNS server apart from its own cache within its local DNS server. By disabling recursion in DNS, your local DNS server might not resolve queries send to the external websites.

First, open this file:

sudo vim /etc/bind/named.conf.options

Then add these options:

recursion no;
version "Not Disclosed";

Restart BIND DNS server

sudo service bind9 restart