What is an Authoritative DNS Server?

What is an Authoritative DNS Server?

• A. A server that holds the original data for a domain.
• B. A server that caches information from other servers.
• C. A server that proxies DNS queries to clients.
• D. A server that only handles subdomain delegations.

Answer: (A)

Authoritative DNS servers are the source of truth for domain information. They store the original zone data for a domain in its zone file and respond with the actual records (such as A, MX, NS, and TXT) for that domain when asked. This is what makes them authoritative for the domain—they provide the definitive answers from the configured data, not from a cache. A server that caches information from other servers isn’t authoritative because its answers come from stored copies of data obtained elsewhere, not from the domain’s own zone data. A server that proxies or forwards queries to clients isn’t providing final DNS answers for the domain. And while authoritative servers can delegate subdomains to other servers via NS records, being authoritative for the domain means maintaining the original data for the domain and responding with those records.

Authoritative DNS servers are the source of truth for domain information. They store the original zone data for a domain in its zone file and respond with the actual records (such as A, MX, NS, and TXT) for that domain when asked. This is what makes them authoritative for the domain—they provide the definitive answers from the configured data, not from a cache.

A server that caches information from other servers isn’t authoritative because its answers come from stored copies of data obtained elsewhere, not from the domain’s own zone data. A server that proxies or forwards queries to clients isn’t providing final DNS answers for the domain. And while authoritative servers can delegate subdomains to other servers via NS records, being authoritative for the domain means maintaining the original data for the domain and responding with those records.