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Handling of Unknown DNS Resource Record (RR) Types (RFC3597)

IP.com Disclosure Number: IPCOM000019265D
Original Publication Date: 2003-Sep-01
Included in the Prior Art Database: 2003-Sep-09
Document File: 9 page(s) / 18K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

A. Gustafsson: AUTHOR

Abstract

Extending the Domain Name System (DNS) with new Resource Record (RR) types currently requires changes to name server software. This document specifies the changes necessary to allow future DNS implementations to handle new RR types transparently.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 19% of the total text.

Network Working Group A. Gustafsson

Request for Comments: 3597 Nominum Inc.

Category: Standards Track September 2003

Handling of Unknown DNS Resource Record (RR) Types

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 (2003). All Rights Reserved.

Abstract

Extending the Domain Name System (DNS) with new Resource Record (RR)

types currently requires changes to name server software. This

document specifies the changes necessary to allow future DNS

implementations to handle new RR types transparently.

1. Introduction

The DNS is designed to be extensible to support new services through

the introduction of new resource record (RR) types. In practice,

deploying a new RR type currently requires changes to the name server

software not only at the authoritative DNS server that is providing

the new information and the client making use of it, but also at all

slave servers for the zone containing it, and in some cases also at

caching name servers and forwarders used by the client.

Because the deployment of new server software is slow and expensive,

the potential of the DNS in supporting new services has never been

fully realized. This memo proposes changes to name servers and to

procedures for defining new RR types aimed at simplifying the future

deployment of new RR types.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",

"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this

document are to be interpreted as described in [RFC 2119].

Gustafsson Standards Track [Page 1]

RFC 3597 Handling of Unknown DNS RR Types September 2003

2. Definition

An "RR of unknown type" is an RR whose RDATA format is not known to

the DNS implementation at hand, and whose type is not an assigned

QTYPE or Meta-TYPE as specified in [RFC 2929] (section 3.1) nor

within the range reserved in that section for assignment only to

QTYPEs and Meta-TYPEs. Such an RR cannot be converted to a type-

specific text format, compressed, or otherwise handled in a type-

specific way.

In the case of a type whose RDATA format is class specific, an RR is

considered to be of unknown type when the RDATA format for that

combination of type and class is not known.

3. Transparency

To enable new RR types to be deployed without server changes, name

servers and resolvers MUST handle RRs of unknown type transparently.

That is, they must treat the RDATA section of such RRs as

unstructured binary data, storing and transmitting it without change

[RFC1123].

To ensure the correct operation of equality comparison (section 6)

and of the DNSSEC canonical form (section 7) when an RR type is known

to some but not all of the servers invol...