Browse Prior Art Database

Classless IN-ADDR.ARPA delegation (RFC2317)

IP.com Disclosure Number: IPCOM000002883D
Original Publication Date: 1998-Mar-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 7 page(s) / 16K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

H. Eidnes: AUTHOR [+3]

Abstract

This document describes a way to do IN-ADDR.ARPA delegation on non- octet boundaries for address spaces covering fewer than 256 addresses. The proposed method should thus remove one of the objections to subnet on non-octet boundaries but perhaps more significantly, make it possible to assign IP address space in smaller chunks than 24-bit prefixes, without losing the ability to delegate authority for the corresponding IN-ADDR.ARPA mappings. The proposed method is fully compatible with the original DNS lookup mechanisms specified in [1], i.e. there is no need to modify the lookup algorithm used, and there should be no need to modify any software which does DNS lookups.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 18% of the total text.

Network Working Group H. Eidnes

Request for Comments: 2317 SINTEF RUNIT

BCP: 20 G. de Groot

Category: Best Current Practice Berkeley Software Design, Inc.

P. Vixie

Internet Software Consortium

March 1998

Classless IN-ADDR.ARPA delegation

Status of this Memo

This document specifies an Internet Best Current Practices for the

Internet Community, and requests discussion and suggestions for

improvements. Distribution of this memo is unlimited.

Copyright Notice

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

2. Introduction

This document describes a way to do IN-ADDR.ARPA delegation on non-

octet boundaries for address spaces covering fewer than 256

addresses. The proposed method should thus remove one of the

objections to subnet on non-octet boundaries but perhaps more

significantly, make it possible to assign IP address space in smaller

chunks than 24-bit prefixes, without losing the ability to delegate

authority for the corresponding IN-ADDR.ARPA mappings. The proposed

method is fully compatible with the original DNS lookup mechanisms

specified in [1], i.e. there is no need to modify the lookup

algorithm used, and there should be no need to modify any software

which does DNS lookups.

The document also discusses some operational considerations to

provide some guidance in implementing this method.

3. Motivation

With the proliferation of classless routing technology, it has become

feasible to assign address space on non-octet boundaries. In case of

a very small organization with only a few hosts, assigning a full

24-bit prefix (what was traditionally referred to as a "class C

network number") often leads to inefficient address space

utilization.

One of the problems encountered when assigning a longer prefix (less

address space) is that it seems impossible for such an organization

to maintain its own reverse ("IN-ADDR.ARPA") zone autonomously. By

use of the reverse delegation method described below, the most

important objection to assignment of longer prefixes to unrelated

organizations can be removed.

Let us assume we have assigned the address spaces to three different

parties as follows:

192.0.2.0/25 to organization A

192.0.2.128/26 to organization B

192.0.2.192/26 to organization C

In the classical approach, this would lead to a single zone like

this:

$ORIGIN 2.0.192.in-addr.arpa.

;

1 PTR host1.A.domain.

2 PTR host2.A.domain.

3 PTR host3.A.domain.

;

129 PTR host1.B.domain.

130 PTR host2.B.domain.

131 PTR host3.B....