PKI: Address Allocation Certificates
Used for verification of an organization's authorization to "advertise" a block of addresses
IANA is root of all addresses
Regional Registries below IANA (Internic, RIPE, and AP-NIC) perform allocation chores today
ISPs nominally receive address blocks from Registries
DSPs and subscribers nominally receive address blocks from ISPs
But, hierarchic allocation not always followed ...
Address space subordination extension (and hardware) can mitigate errors by registries, ISPs and DSPs