Some times, we are required to resolve our internal domains on a local nameserver and external (internet) domains on our ISP's nameserver. There are different solutions to this problem, but in this howto, we are going to solve it through configuring a combination of caching-nameserver and BIND 9.
BIND 9 is used to resolve domain resolution queries from it own database, as it is SOA (Start Of Authority).
So now it is clear that in our setup the caching-nameserver will be used to resolve domain names externally (internet), while BIND 9 will be used to resolve domain names from our local network (internally).
Now we have caching-nameserver and BIND 9 hammer in our hands, lets start fixing it.