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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  Name Systems and TCP/IP Name Registration and Name Resolution            9  TCP/IP Name Systems: Host Tables and Domain Name System (DNS)                 9  TCP/IP Domain Name System (DNS)                      9  DNS Name Registration, Public Administration, Zones and Authorities

DNS Organizational (Generic) Top Level Domains and Authorities 1 2 3 4 DNS Second-Level and Lower Domains, Delegation of Registration Authority and Public Registration

Geopolitical (Country Code) Top Level Domains

For these and other reasons, the Internet's name space was set up with a set of country-code top-level domains paralleling the generic ones, sometimes called ccTLDs. I call these geopolitical TLDs since they are based on geopolitical divisions of the world (similar to the example I used in my overview of the DNS name space). In this hierarchy, every country of the world is assigned a particular two-letter code as a top-level domain, with a specific authority put in charge of administering the domain. For example, the ccTLD for Great Britain is “.UK”, the one for Canada “.CA” and the one for Japan is “.JP”. The codes often are more meaningful in the local language than in English, incidentally; Germany's is “.DE” and Switzerland's “.CH”.

When I said that countries rarely agree on anything, I wasn't kidding—in fact, they can't even agree on what's a country! Real shooting wars have been fought over whether or not a particular territory was independent or part of another nation, never mind verbal wars, and the creators of DNS wanted no part of this sort of controversy. As the IANA web site says:

“The IANA is not in the business of deciding what is and what is not a country, nor what code letters are appropriate for a particular country.”

To remain neutral, IANA’s ccTLD codes are taken directly from the standard country abbreviations maintained by the International Organization for Standardization (ISO) in ISO standard 3166-1. When a country is recognized by the ISO and a code assigned to it on this list, IANA creates it as a top-level domain. There are presently over 200 different geopolitical TLDs. No, I am not putting them here in a table, I have to draw the line somewhere around here! J

DNS Organizational (Generic) Top Level Domains and Authorities 1 2 3 4 DNS Second-Level and Lower Domains, Delegation of Registration Authority and Public Registration