IXFR (Incremental Zone Transfer)

What is IXFR (Incremental Zone Transfer)?

IXFR (Incremental Zone Transfer) is a method used in the DNS to transfer only the changes made to a zone file since the last full transfer. This allows for more efficient updates to DNS records, as only the modified data needs to be transferred rather than the entire zone file. IXFR is commonly used in environments where frequent updates to DNS records are made, such as dynamic DNS configurations or large-scale networks with multiple DNS servers.

When a DNS server initiates an IXFR request, it compares the serial number of the zone file on the primary server with the serial number of the zone file on the secondary server. If the serial numbers do not match, the primary server sends only the incremental changes to the secondary server. This process reduces the amount of data that needs to be transferred, resulting in faster updates and reduced network traffic.

IXFR is supported by most modern DNS servers and is specified in RFC 1995. It provides a more efficient and reliable method for updating DNS records compared to traditional full zone transfers. By using IXFR, administrators can ensure that changes to DNS records are propagated quickly and accurately throughout the network, improving overall performance and reliability of the DNS infrastructure.