authoritative name server
A Domain Name System (DNS) server that hosts the official database of resource records (the registry) for a DNS zone. The registry identifies the Internet Protocol (IP) addresses of the host servers (e.g., web servers, mail servers) and name servers in the authoritative name server’s zone. The resource records in its registry enable an authoritative name server to respond definitively to queries about the servers and subdomains within its zone.
To enable other computers to reach host servers within a domain, the domain must have one or more authoritative name servers. The name and IP addresses of those servers must also appear in the registry of the domain’s parent domain.