In DNS, zone transfers are typically conducted between which types of servers?

• A. Between recursive resolvers.
• B. Between clients and servers.
• C. Between two identical DNS servers to synchronize caches.
• D. Between primary and secondary DNS servers.

Answer: (D)

Zone data replication is what’s being tested. Zone transfers move the authoritative DNS records for a zone from the primary (master) server to one or more secondary (slave) servers to keep all copies consistent and available. This mechanism ensures that if the primary goes down, the secondary can continue answering queries with the same up-to-date data. Transfers use AXFR for a full copy or IXFR for incremental updates. It isn’t about recursive resolvers sharing data, nor about clients talking to servers for data, and caches on resolvers aren’t the same as authoritative zone data being replicated between servers.