[cestith]

I can think of use cases with existing solutions that could migrate to something like this, but not any really novel use cases. Put your health checks in your DNS server rather than issuing nsupdate requests from a monitoring system. Use this to do GeoDNS dynamically in the DNS server rather than using anycast and giving out different records at different authoritative DNS servers. Check the netblock or ASN-1 of someone connecting and direct traffic from specific networks to different host records. Automatically adjust your TTL upward when you're getting a lot of DNS traffic for a particular record. Adjust it down when adding new A records to a particular name. Have fine-grained control over logging for just certain requests. Automatically have SPF and DKIM updated when adding records to a particular subzone.