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Networking Fundamentals · Intermediate

Zone Transfer

Replication of DNS zone data from a primary to secondary servers, as a full transfer (AXFR) or incremental transfer (IXFR), over TCP 53.

Definition

Zone transfers should be restricted to authorized secondary servers, because an unrestricted transfer exposes the full list of hosts to attackers.

Example

dig axfr example.com @ns1.example.com requests a full zone transfer.

Exam tip

Zone transfers use TCP 53; restrict them to known secondaries.

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