What does a higher primary SOA indicate in a DNS setup?

• A. The primary server has more recent information than the secondary server.
• B. The primary server is offline.
• C. The secondary server holds more recent data.
• D. Both servers are in sync.

Answer: (A)

The serial number inside the DNS SOA record acts as a version indicator for the zone data. The primary (master) server holds the authoritative copy, and whenever you update the zone on the primary, you increment its serial. Secondary (slave) servers periodically compare their own zone serial to the primary’s; if their serial is older, they pull updates to catch up.

So a higher serial on the primary means its data is more recent than the secondary’s, and the secondary should be updated to reflect those changes. If both were truly in sync, the serials would be the same. If the secondary held newer data, its serial would be higher or the primary’s lower, which isn’t the case here.