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Frequently asked Questions.

The INAIC is a public information resource for Internet users worldwide and we welcome your question and comments. If there are any issues we have not addressed please click here and help us build our FAQ. Contributions from the Internet community are always welcomed. The "Six Most Frequently Asked Questions" are on the main page of the INAIC web site, the rest is displayed here.

What is a "TLD", an "SLD", a "3LD"?

TLD stands for "Top-Level Domain". in the taxonomy of the Internet's DNS name space it is the part of a domain name that is furthest to the right of a character based, human-readable address string.

Most people are familiar with TLDs such as .COM; .NET; .ORG marketed as a "Generic" TLD (gTLD) as opposed to a "Country Code" TLD (ccTLD) like .AU; (for Australia); .UK (for Great Britain); and .TV (For Tuvalu), etc.

Several thousands of TLDs exist - not just the gTLDs and ccTLDs - and the Public-Root resolves all these TLDs on a global scale planet.

An "SLD" is a "Second-Level Domain", and is commonly recognized by some sort of associative string that indicates it's respective registrant in the form of a company name, product, or person.

Examples of SLDs that most people are familiar with are "IBM", "MapQuest", or "Yahoo" and appear in context with their 'parent' zone, the TLD it is anchored to: i.e., IBM.COM, MapQuest.COM, and Yahoo.COM.

Many countries organize their respective domain space by creating a domain space with generic SLDs under their ccTLD. Great Britain and Australia are examples of ccTLD operators that specify such organizational standards in the naming conventions for the DNS zones they administer.

For example, YellowPages.COM.AU, or IBM.CO.UK are examples of this sort of organizational structure. In such schematas, one cannot simply register an SLD because the SLDs are closed zones that are themselves registries for 3LDs, or, "3rd-Level Domains".

3LDs do not necessarily have to adhere to a conventional standard specified by the governmental administrator/operator of a ccTLD. They can occur under gTLDs as well, and in fact many organizations and even small companies incorporate the use of 3LDs (and even 4LDs and beyond) in their corporate or university naming hierarchies. Examples of this include barney.ochem-lab.math-physics.ucla.edu, where 'barney' is the hostname of the machine, ochem-lab is probably the Organic Chemistry laboratory in the math and physics building at the University of California in Los Angeles.

The example above demonstrates the hierarchy of the domain space, and in this case is indicative of a structure that utilizes a hostname, 4LD, 3LD, and SLD, under the .EDU TLD. Although college students have been accustomed to such organizational conventions in the DNS namespace for years, most average consumers are usually only likely to run across hostnames under SLDs such as www.IBM.com, www.Google.com, etc., the hostname in both instances here being "www", and the SLDs under the .COM TLD being, "IBM", and "Google", respectively.

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