Which DNS record contains the Start of Authority data for a zone?

Which DNS record contains the Start of Authority data for a zone?

• A. A
• B. PTR
• C. NS
• D. SOA

Answer: (D)

The Start of Authority data for a zone is stored in the SOA record at the zone’s apex. This record carries essential metadata that governs how the zone is managed and replicated, including the serial number (which increments when the zone data changes), refresh and retry intervals (telling secondaries when and how often to check for updates), expiry time, and the negative caching TTL. It also identifies the primary name server and the contact email for the zone administrator. This information is what DNS servers use to coordinate zone transfers and ensure consistency across servers. A records map names to IPv4 addresses, PTR records handle reverse lookups from IP to name, and NS records designate which servers are authoritative for the zone. None of these contain the Start of Authority metadata, which is specifically held in the SOA record.

The Start of Authority data for a zone is stored in the SOA record at the zone’s apex. This record carries essential metadata that governs how the zone is managed and replicated, including the serial number (which increments when the zone data changes), refresh and retry intervals (telling secondaries when and how often to check for updates), expiry time, and the negative caching TTL. It also identifies the primary name server and the contact email for the zone administrator. This information is what DNS servers use to coordinate zone transfers and ensure consistency across servers.

A records map names to IPv4 addresses, PTR records handle reverse lookups from IP to name, and NS records designate which servers are authoritative for the zone. None of these contain the Start of Authority metadata, which is specifically held in the SOA record.