A DNS server or names server is a computer connected to the Internet. It contains information about the services related to a domain name and answers any queries about this information. For example, it translates a domain name into an IP address to enable access to a website/s and/or email inboxes linked to a domain name.

The NSTest server is a service that enables registrars to test the correct configuration of their names servers. It ensures that they comply with the technical requirements set by the domain name registry before validating the DNS delegation. Success in this testing phase guarantees registrars that all the domains they manage will be published in the root zone.