Which statement best describes an authoritative DNS server?

• A. It holds the original data for a domain.
• B. It caches information from other servers.
• C. It translates domain names to IP addresses for clients.
• D. It routes mail for the domain.

Answer: (A)

An authoritative DNS server is the source of truth for a domain because it stores the original zone data for that domain. It holds all the actual DNS records for the zone (such as A, AAAA, MX, NS, SOA, etc.) and can answer queries definitively based on those records without needing to ask another server.

In contrast, caching or recursive resolvers do not maintain the domain’s original data; they fetch records from authoritative servers and cache them to speed up responses. They may wind up giving answers that depend on what they’ve cached, which might not always reflect the current zone data.

Translating domain names to IP addresses is a function performed by resolvers using data from authoritative servers, not a defining trait of being authoritative. And while MX records determine mail routing, that routing is just one type of data an authoritative server may host, not the defining role.