Zone Transfer

A Zone Transfer is a Domain Name System, or DNS, mechanism used to transfer DNS zone data between authoritative DNS servers. It enables primary and secondary DNS servers to keep their zone information synchronised. A full zone transfer using AXFR transfers the complete zone, while IXFR provides an incremental transfer containing only changes made since a previous version of the zone data. Zone Transfers play an important role in maintaining the redundancy and availability of DNS infrastructures. As zone data can contain information about hosts and services associated with a domain, transfers should only be permitted between authorised DNS servers. Access controls, IP-based restrictions and cryptographic mechanisms such as TSIG can help prevent unauthorised Zone Transfers.