DNS zone transfer
(also AXFR)
DNS zone transfer definition
A DNS zone transfer is a type of DNS transaction you can implement. With a DNS zone transfer, primary and secondary DNS servers can exchange zones with each other, including all resource records, which is a critical requirement for redundancy and backup for DNS data. DNS zone transfers are usually done to replicate DNS data to a number of different DNS servers. It can also distribute DNS updates and changes across multiple servers.
Usually, records from the primary DNS server are shared with secondary and other DNS servers during a DNS zone transfer. A DNS zone transfer is usually a very long and time-consuming process, so organizations started implementing incremental DNS zones, which transfer only the changes since the previous transfers to speed up the process and save time.
See also: DNS filtering, DNS server
DNS zone transfer records
SOA record. An SOA (state of authority) is a mandatory DNS record and serves as the starting point for a DNS zone. It contains information like the name of the server, the name of the administrator of the DNS zone, the current SOA record version, the amount of time (in seconds) that a secondary DNS server needs to wait before checking for updates, and the amount of time (in seconds) to wait before trying a failed transfer again. Its purpose is to indicate the authoritative DNS server for the zone, manage zone parameters, and facilitate zone transfer.
MX record. The MX (mail exchange) record determines which mail server must accept email messages on behalf of a domain name. It allows email to be routed correctly by specifying the priority of multiple mail servers for a domain.
TXT record. The TXT (text) record allows you to associate arbitrary text with names or a host. It can contain valuable information, like data center information, domain ownership verification, network information, and other account information.