1. Introduction

For rapid propagation of changes to a DNS database [STD13], it is necessary to reduce latency by actively notifying servers of the change. This is accomplished by the NOTIFY extension of the DNS [NOTIFY].

The current full zone transfer mechanism (AXFR) is not an efficient means to propagate changes to a small part of a zone, as it transfers the entire zone file.

Incremental transfer (IXFR) as proposed is a more efficient mechanism, as it transfers only the changed portion(s) of a zone.

In this document, a secondary name server which requests IXFR is called an IXFR client and a primary or secondary name server which responds to the request is called an IXFR server.