Private Domain Name Registries are organisations that run the root DNS servers for domain names that are not part of the "official" (i.e., ICANN approved) DNS namespace.
Private DNS registries can be classified into two types:
- those which expand the DNS namespace "downwards" by registering domain names as subdomains of existing top level domains (TLDs);
- those which expand the DNS "outwards" by creating their own TLDs and running the root servers for them.
As a rule, DNS geeks tend to grudgingly accept the first kind, and vociferously oppose the second, the reason being that the "outwards" registries' TLDs are outside of the DNS system and cannot be accessed without using an ISP that's been paid off to include them (for example, Freeserve, who were allegedly paid £1 million by new.net) in their DNS servers, or a platform specific browser plug-in.
The main private registries are:
- CentralNic*: established in 1995 to sell .uk.com domain names (inspired by a suggestion from Jon Postel - at the time Nominet were selling .co.uks for £300), CentralNic is now the world's largest private domain name registry, operating eighteen global domain names, including .us.com, .eu.com and .de.com.
- eu.org offers free .eu.org domains to not-for-profit organizations and individuals since 1996 (approx).
- NetRegistry: operates .jp.com and .au.com, to compete with the very restrictive rules on .com.au.
- new.net: operates 46 TLDs outside the regular DNS system, including .shop, .church, .love and .xxx.
Prices for domains from private registries tend to be higher than from the others, due to the increased availability of names within their namespace.
There are also a number of alternative namespaces run on a not for profit basis. These include:
- OpenNic supports the legacy U.S. Government DNS, and provides .indy, .geek, .oss and .bbs, among others.
- AlterNic provide .nic, .ltd, and .porn. They also operate their own .xxx TLD in conflict with new.net's.
Unlike the "outwards" registries mentioned above, these alternative namespaces prefer to operate using internet standards - you don't need a plugin to access them, just add their root servers to your DNS config. They're also committed to not conflicting with the official ICANN domains.
*: I should say right now that I work for CentralNic, so if this writeup seems a bit biased, it probably is. We rule.