The Internet Corporation for Assigned Names and Numbers (ICANN) is directly responsible for the operations of the Internet Assigned Numbers Authority (IANA).
It is tasked to oversee the allocation of duties pertaining to the management of the bulk of top level domains to organizations deemed to be professional in their conduct – the IANA manages the DNS Root Zone.
Domain names derive the top level status based on the COM in the www.yoursite.com as domain names are not relative to its status level placement, and as you might be well aware the domain name system assigns respective countries their distinct two letter ISO country code, and these are referred to as country code top level domains (ccTLD).
The categories group are the generic top level domains and from the early days it was made up of .edu, .com, .mil, .gov. .org and .net. As time went on the necessity for more generic top level domains became more apparent and pressing, this ultimately led to considerations of effecting changes in assigning, modifying and generalizing domain purposes.
Several top level domains as they are categorized by the Internet Assigned Numbers Authority are as follows – country code top level domains (ccTLD), generic top level domains (gTLD), three more characters unsponsored top level domains, sponsored top level domains (sTLD).
This category consists of proposed and sponsored domains by private entities. The internationalized domain name (IDN) have been established on a trial basis and the initial top level domain -arpa, is currently employed in the internet infrastructure purposes such as in – addv. arpa for IPv4 and IP6.arpa for IPv6 reverse DNS resolution, uri.arpa plus urn.arpa for the Dynamic Delegation Discovery System.
The e164.arpa for telephone number mapping, it was once utilized for reverse DNS lookup. Some top level domain names are selectively reserved for pertinent purposes of preventing confusion and conflict.
And these are for example, invalid, local host and test, there are several historical domains and they include nato, cs for Czechoslovakia now cz for Czech Republic, sk for Slovak Republic, dd for East Germany now de (Germany) and zr for Zaire now cd for Democratic Republic of Congo.
However, despite the end of the Soviet Union the TLD .su is still in active use. The Communications Decency Act of 1996 has been raised by people advocating for the allocation of TLD’s such as xxx, for sex and adult sites containing content of an obscene nature.
And this was after the introduction of the TLD’s aero, biz, coop, info, and pro by the ICANN. The creation of alternate DNS roots with different sets of top level domains was necessitated by the high application costs of TLD’s and ICANN’s apparent snail’s pace in the creation of requested generic top level domains.