What is a DNS zone transfer?

What is a DNS zone transfer?

• A. Querying a DNS server to resolve a domain name.
• B. Copying DNS zone data from a primary to a secondary DNS server.
• C. Updating a DNS record in real time.
• D. Transferring DNS zone data from a client to a server.

Answer: (B)

DNS zone transfer is the process of copying the data for a DNS zone from a primary (master) server to one or more secondary (slave) servers to keep all copies in sync. This replication supports redundancy and load distribution: if the primary becomes unavailable, secondaries can still respond to queries, and updates are shared across servers. The primary indicates changes with an SOA serial number, and secondaries pull updates when notified, either as a full transfer (AXFR) or incremental changes (IXFR). Because a zone transfer exposes all the zone’s records, access is typically restricted to trusted servers and may be authenticated with mechanisms like TSIG. This is different from ordinary DNS queries or dynamic in-place record updates, which are about resolving names or updating records in real time, not replicating the entire zone.

DNS zone transfer is the process of copying the data for a DNS zone from a primary (master) server to one or more secondary (slave) servers to keep all copies in sync. This replication supports redundancy and load distribution: if the primary becomes unavailable, secondaries can still respond to queries, and updates are shared across servers. The primary indicates changes with an SOA serial number, and secondaries pull updates when notified, either as a full transfer (AXFR) or incremental changes (IXFR). Because a zone transfer exposes all the zone’s records, access is typically restricted to trusted servers and may be authenticated with mechanisms like TSIG. This is different from ordinary DNS queries or dynamic in-place record updates, which are about resolving names or updating records in real time, not replicating the entire zone.