DNS zone transfer

DNS zone transfer, also sometimes known by the inducing DNS query type AXFR, is a type of DNS transaction. It is one of the many mechanisms available for administrators to replicate DNS databases across a set of DNS servers.

A zone transfer uses the Transmission Control Protocol (TCP) for transport,^[1][2] and takes the form of a client–server transaction. The client requesting a zone transfer may be a secondary server requesting data from a primary server.^[3] The portion of the database that is replicated is a zone.