AXFR (Full Zone Transfer)

What is AXFR (Full Zone Transfer)?

AXFR (Full Zone Transfer) is a protocol used in the DNS to transfer an entire zone file from one DNS server to another. This process allows for the synchronization of DNS records between servers, ensuring that all servers have the most up-to-date information about a domain's DNS records. AXFR is typically used when setting up a new DNS server, migrating DNS records to a new server, or when making significant changes to a domain's DNS configuration.

During an AXFR transfer, the requesting server sends a query to the server hosting the zone file, requesting all the DNS records for that domain. The server hosting the zone file then responds with the complete set of DNS records, which are transferred in a sequential manner. This process ensures that the receiving server has an exact copy of the zone file, allowing for seamless DNS resolution across multiple servers.

AXFR transfers are typically used between authoritative DNS servers, which are responsible for providing authoritative answers to DNS queries. It is important to note that AXFR transfers can potentially be a security risk, as they expose the entire zone file to potential attackers. To mitigate this risk, it is recommended to use secure transfer methods such as TSIG (Transaction Signature) or DNSSEC (Domain Name System Security Extensions) when performing AXFR transfers.