> Reverse delegation (RFC 2317) is the way IP-to-FQDN lookups are usually done now

> Before this was popular, you could get your ISP to defer to your DNS for reverse records directly

I'm not actually seeing the difference between these two... besides this new "reverse delegation" allowing different nameservers for prefixes longer than /24... aren't you still relying on your ISP/upstream provider (if you don't own your own IPs) to delegate reverse lookups to your own DNS server either way?