Which of the following is a read-only copy of a zone and obtains its resource records from other name servers?

A secondary zone is also read-only and receives records via zone transfer, but it holds a complete copy of all resource records from the primary zone, not just the NS/SOA subset.

A primary zone is the authoritative read-write source of zone data where records are created, modified, and deleted directly.

A stub zone contains only the SOA record, NS records, and the glue A records needed to identify authoritative name servers - it does not hold the full set of resource records. It obtains and refreshes these records from a master name server, making it read-only by design. Stub zones are used to keep name server delegations current and to reduce recursive query load across zone boundaries.

SOA zone is not a valid DNS zone type; SOA (Start of Authority) is a resource record that appears within a zone, not a zone classification.