In DNS, what does SOA stand for?

• A. Start of Authority
• B. Source of Authority
• C. System of Authentication
• D. Start of Authority Record

Answer: (A)

SOA stands for Start of Authority. This DNS resource record marks the beginning of a zone and identifies the primary (authoritative) name server for that zone, along with the zone administrator’s contact information. It also carries important administrative data used to manage zone transfers and caching: a serial number that increases with each zone update, and timing parameters such as refresh, retry, expire, and minimum TTL. These values tell secondary (slave) servers how often to check for updates and how long they can serve data if the primary becomes unavailable.

That’s why this option is the best fit: it precisely names the function and role of this record in DNS. The other phrases don’t correspond to the standard DNS term—“Source of Authority” and “System of Authentication” aren’t used in DNS, and while you’ll often hear about the “SOA record,” the canonical expansion is Start of Authority, not Start of Authority Record.