Hardware-based implementations run distinct DNS server devices for the desired access granularity within the networks involved.
By using split-horizon DNS the same name can lead to either the private IP address or the public one, depending on which client sends the query.
As an example, the DNS server could be configured to return two different sets of records for the host host1.example.net for requestees internal and external to a corporate network.
These apparently conflicting goals create the potential for confusion or false security alerts in poorly constructed networks.
Hardware-based implementations run distinct DNS server devices for the desired access granularity within the networks involved.