These are test domain extensions and are not available for registration.
As of June, IANA listed 1,584 domain extensions . These include 55 unassigned (revoked), 8 retired, and 11 test extensions, none of which are listed by ICANN. You can view the full list of domains in the IANA root database.
Can I use any extension for my domain?
Just because a domain extension is available doesn't mean you can buy it. We can differentiate between unrestricted and restricted domain extensions .
The former can be purchased and registered by any person or croatia business email database organization, while the latter are restricted to certain types of companies, organizations and groups, which must meet specific requirements.
Usage restrictions depend on the organization that manages the TLD. For example, .aero is managed by SITA, which restricts its use to companies related to the aeronautical sector.
This doesn't only apply to generic TLDs, but restrictions also apply to countries . For example, to use the .us or .eu extension, you must be able to prove your presence in the US or the European Union. However, to use the .es, .mx or .nl extension, there are no restrictions at all . That's why you should analyze your domain and know the requirements of your TLD before you try to register it.