Which statement best describes a DNS zone transfer?

• A. Querying a DNS server for A records.
• B. Performing a reverse DNS lookup.
• C. Transferring the complete zone data from one DNS server to another.
• D. Querying MX records for a domain.

Answer: (C)

DNS zone transfer is the mechanism by which the complete set of DNS records for a domain (the zone) is copied from a primary DNS server to a secondary DNS server to keep them in sync and ensure availability. This is typically used to replicate the zone across multiple servers, and it can be performed as a full transfer (AXFR) or an incremental transfer (IXFR). The statement describing transferring the complete zone data from one DNS server to another best captures this concept. The other options describe specific DNS lookups that retrieve individual records rather than the entire zone data. Note that if zone transfers are improperly allowed to third parties, an attacker could enumerate all records in a domain.