An authoritative name server is a DNS server that stores and answers with the official records for a domain or zone it manages. When it receives a query for that domain, it returns the canonical data, such as A, AAAA, MX, and NS records, rather than guessing or forwarding the request elsewhere.
This role matters because authoritative servers are a trust anchor for name resolution: if they fail, the domain can become unreachable even when other systems are healthy. Attackers often target them with denial-of-service traffic, malformed queries, or resource-exhaustion bugs to disrupt websites, mail, and APIs. Defenders harden authoritative servers with patching, rate limits, redundancy, and monitoring for crashes, restart loops, or abnormal latency. In practice, protecting authoritative DNS is protecting the visibility and availability of the services behind the domain.