A pool of ‘private’ DNS servers. These servers would typically allow non standard TLDs (.dev , .local etc), and may not have the same level of blacklist restrictions. They would be aimed at people with Neutron Networking, and VPC style set ups, where access to the DNS server would come from trusted networks (E.G. in-cloud - owned instances, and onsite resources connect by VPN)
This would allow customers to set DNS entries for internal servers, on domains that would not be available on the public pools, and have them accessible by internal users