The top-level domain (TLD) for the Cook Islands, a sovereign island country in the South Pacific Ocean, is .CK. This Internet country code top-level domain (ccTLD) was delegated to the Cook Islands in 1995 and is managed, according to data from the Internet Assigned Numbers Authority (IANA), by one of the Cook Islands government’s entities—the Office of the Deputy Government Chief Information Officer. This office falls under the purview of the Office of the Prime Minister.
As part of the standard procedures for top-level domain administration established by the IANA and ICANN (Internet Corporation for Assigned Names and Numbers), the domain .CK, like other national domains, exists to serve the internet users of a specific country, in this case, the Cook Islands.
According to the registry rules shared by the Cook Islands government, third level registrations are available beneath these second level names: .co.ck, .org.ck, .edu.ck, .gov.ck, and .net.ck. For example, a commercial entity could register a domain like example.co.ck. However, there are specific requirements to be met while registering .CK domains, such as the owner’s contact information being located in the Cook Islands.
Because of its unique string (‘ck’), this ccTLD domain is also used by some businesses unrelated to the Cook Islands, often for domain hacks, usually for cookbooks or cooking-related websites (example: babycake.ck).
One should be aware that registering a country-specific top-level domain like .CK can also have cultural, political, or public relations ramifications as it can be seen as a statement about the geographic or national affiliations of the organization or individual that registers it.
Sources:
1. [IANA — .ck Domain Delegation Data](https://data.iana.org/TLD/tlds-alpha-by-domain.txt)
2. [ICANN.org](https://icann.org/)
3. [Universal Postal Union](http://www.upu.int/en/activities/philately/products-and-services/-cook-islands-post-limited.html)
4. [.ck (Wikipedia)](https://en.wikipedia.org/wiki/.ck)
5. [Office of the Prime Minister, Cook Islands](http://www.pmoffice.gov.ck/)
6. [NIC.CK (Cook Islands Network Information Centre)](https://www.nic.ck/rules.html)
