IANA

IANA (Internet Assigned Numbers Authority) is the function that keeps the master registries of unique identifiers that make the internet interoperable. That includes IPv4 and IPv6 address blocks (which IANA allocates to the five RIRs), AS numbers, port numbers, protocol parameters, and most importantly the DNS root zone, including the list of all TLDs and their nameserver delegations. IANA is operated by ICANN under a contract with the US National Telecommunications and Information Administration that transitioned to a multi-stakeholder model in 2016. Every TLD listed in the dnschkr directory ultimately traces back to an IANA root zone entry.