Conditional forwarders
In DNS servers, we use DNS "forwarders" to forward DNS queries to external DNS servers when it can't resolve them internally. Usually it will be the ISP's public DNS servers. We also can use public DNS servers from a third party such as Google as a forwarder:
Figure 4.9: DNS forwarders
If the forwarders are not responding, the DNS server will use "Root Hints" to resolve the query.
Forwarders and Root Hints are used to resolve external DNS queries in general. But if we need to point DNS queries for a specific domain to a specific DNS server/s we can do that using "conditional forwarders." As an example, there is a partner company with the rebeladmin.net domain name. Their DNS server is 10.0.0.5. These two organizations are connected together via a VPN connection. So if any user in the rebeladmin.com domain tries to resolve the hostname in rebeladmin.net, it should forward to 10.0.0.5. To do that we can...
