The Internet Assigned Numbers Authority (IANA) also delegates authority to other organizations and companies to grant users unique IP address blocks and register domain names. IANA is the ultimate authority for managing the root name servers that maintain the central database of information for the DNS.
IANA also controls the assignment of TCP/IP protocol identifiers and numbers for autonomous systems on the Internet.
IANA operates under the auspices of the Internet Society (ISOC). It is also considered part of the Internet Architecture Board (IAB). IANA delegates the responsibilities for managing IP and DNS space to three regional bodies:
The American Registry for Internet Numbers (ARIN), which manages North America, South America, and sub-Saharan Africa