RFC 1996 (rfc1996) - Page 1 of 7


A Mechanism for Prompt Notification of Zone Changes (DNS NOTIFY)



Alternative Format: Original Text Document



Network Working Group                                           P. Vixie
Request for Comments: 1996                                           ISC
Updates: 1035                                                August 1996
Category: Standards Track


    A Mechanism for Prompt Notification of Zone Changes (DNS NOTIFY)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   This memo describes the NOTIFY opcode for DNS, by which a master
   server advises a set of slave servers that the master's data has been
   changed and that a query should be initiated to discover the new
   data.

1. Rationale and Scope

   1.1. Slow propagation of new and changed data in a DNS zone can be
   due to a zone's relatively long refresh times.  Longer refresh times
   are beneficial in that they reduce load on the master servers, but
   that benefit comes at the cost of long intervals of incoherence among
   authority servers whenever the zone is updated.

   1.2. The DNS NOTIFY transaction allows master servers to inform slave
   servers when the zone has changed -- an interrupt as opposed to poll
   model -- which it is hoped will reduce propagation delay while not
   unduly increasing the masters' load.  This specification only allows
   slaves to be notified of SOA RR changes, but the architechture of
   NOTIFY is intended to be extensible to other RR types.

   1.3. This document intentionally gives more definition to the roles
   of "Master," "Slave" and "Stealth" servers, their enumeration in NS
   RRs, and the SOA MNAME field.  In that sense, this document can be
   considered an addendum to [RFC 1035].









Vixie                       Standards Track