TLD Classification Glossary

adoptabledomains · Nov 12, 2002

After reading the new recommendations of ICANN, It seemed to me some new acronyms and descriptions of TLDS (Top Level Domains) that have been used. I thought I'd summarize what I'd been reading as sort of a glossary:

gTLD - Generic Top Level Domain (.com, .net, .org, .info) Gloablally open, few rules of regitstration or use.
sTLD - Sponsored generic TLD (aka: sgTLD)(.museum, .coop, .aero, .pro) Domains controlled by a group who sets rules for who can get them and for what purpose, usually by members.
uTLD - Unsponsored TLD - any TLD not controlled by a membership sponsoring organization.
rTLD - Restricted TLD (.biz, .name) a TLD that is not a sponsored generic domain but is somewhat restricted to what it's use may be. Dot-biz has rules that it must be business related, dot-name is purposed for personal websites and mail.
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ccTLD - County Code TLD (.us, .ca, .co.uk, .mx, etc.) Country codes originally assigned to control of a country. (.eu or European Union will be a slight variation of this as a group of countries)
Repurposed ccTLD - Country code TLD's released by the country to commercial global use (.tv, .cc, .ws, etc.)
Unresticted ccTLD - Country code TLD in which anyone, anywhere can register any number of names (.bz, .sc, .tv)
Semi-restricted ccTLD - Country domain that normally requires local presence (the new .us, .co.uk, .au)
Restricted ccTLD - a Country code domain highly controlled and normally only allowed one per citizen/business of that country, sometimes with strict naming conventions, use verification, etc. (.ky; .jp, and .us until recently)

There have also been proposals (none yet approved) of special use or service TLD's like .tel that would link to assigned telephone numbers or VOIP, and .wap that would be for wireless access protocol.

Alternate/Alternative/nonexclusive root domains created by providers of unapproved domains not served by the "approved/exclusive" root servers. (They require special DNS settings at the ISP or browser plugins to work). Pacific Root and New.net are two providers of these TLD's... Kind of the non-conformists or outlaws of the domain world. Maybe these should be coined altTLD's (kind of like the split of alt. class of newsgroups from way back, huh?)

Thought this might be useful to newbies and others who are confused by evolution of the TLD terminology. Did I miss anything?

MarkMitford · Nov 13, 2002

.co.uk is unrestricted not semi-restricted.

dtobias · Nov 13, 2002

.co.uk is technically a second-level domain, not a TLD. (A number of ccTLDs have subdivisions at the second level like this; for instance .au has .com.au, .org.au, etc.)

Where do .EDU, .GOV, .MIL, and .INT fit in? Like .COM, .NET, and .ORG, they predate the current classifications and ICANN contracts, so they don't fit as well into the current categories. However, since its recent redelegation, .EDU is being operated pretty much like a sponsored, restricted domain (though under the oversight of the US government instead of ICANN, and restricted to US educational institutions), .INT is run directly by the IANA function of ICANN as a highly restricted domain with no separate registry or registrars, and .GOV and .MIL are special cases run directly by the U.S. government.

dtobias · Nov 13, 2002

Also, .ARPA exists as a "special use or service TLD", hosting network infrastructure functions (most notably IN-ADDR.ARPA, used for reverse lookup of domains from IP addresses).