In DNS, what is the purpose of a zone transfer?

• A. To block DNS queries from external networks.
• B. To replicate DNS records from a primary DNS server to a secondary DNS server.
• C. To back up email data.
• D. To resolve domain names to IP addresses.

Answer: (B)

Transferring a DNS zone is about duplicating the DNS data from the primary server to a secondary server. This keeps both servers in sync so there are multiple authoritative sources for the same zone, which improves redundancy and availability. The process can be full or incremental, and the data being copied are the zone records, not the way names are resolved or emails backed up. In other words, a zone transfer ensures secondary servers have up-to-date DNS records so they can respond if the primary is unavailable.