RFC 2308 (rfc2308) - Page 1 of 19

Negative Caching of DNS Queries (DNS NCACHE)

Alternative Format: Original Text Document
Next >
Network Working Group                                          M. Andrews
Request for Comments: 2308                                          CSIRO
Updates: 1034, 1035                                            March 1998
Category: Standards Track


              Negative Caching of DNS Queries (DNS NCACHE)

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.

Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

Abstract

   [RFC 1034] provided a description of how to cache negative responses.
   It however had a fundamental flaw in that it did not allow a name
   server to hand out those cached responses to other resolvers, thereby
   greatly reducing the effect of the caching.  This document addresses
   issues raise in the light of experience and replaces [RFC 1034 Section
   4.3.4].

   Negative caching was an optional part of the DNS specification and
   deals with the caching of the non-existence of an RRset [RFC 2181] or
   domain name.

   Negative caching is useful as it reduces the response time for
   negative answers.  It also reduces the number of messages that have
   to be sent between resolvers and name servers hence overall network
   traffic.  A large proportion of DNS traffic on the Internet could be
   eliminated if all resolvers implemented negative caching.  With this
   in mind negative caching should no longer be seen as an optional part
   of a DNS resolver.











Andrews                     Standards Track
Next >