The Internet Assigned Number Authority (IANA) recently released a root domain database detailing the current status of all 273 top-level domains, including four generic top-level domains, three restricted generic domains, 251 country domains, 13 organizational domains, and two more special ones: One is.au, the Australian Domain Name Authority, which is the same as the Australian national domain name. The second is.arpa, reserved domain name used for reverse domain name resolution.