Also known as split-view DNS, split DNS or DNS multi-view.
The Main Objective of Split-horizon DNS:
To use different EXTERNAL and INTERNAL files to differrequest originating from Internet and local net.Make sure you use BIND9 or newer to support Split-horizon DNS.
The key moment in Split-horizon DNS:
As you can see on the setup above the external xfer is done by a different IP address on the secondary DNS server which allows Primary DNS server to differ the INTERNAL and EXTERNAL files.So to the basic you have to have two DNS files on the primary DNS server and let’s say you named them external.mydomain and internal.mydomain.The external.mydomain will contain only external IP addresses and internal.mydomain will contain only internal IP addresses.