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Binary Labels in the Domain Name System (RFC2673) Disclosure Number: IPCOM000003264D
Original Publication Date: 1999-Aug-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 5 page(s) / 11K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

M. Crawford: AUTHOR


Status of this Memo

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 26% of the total text.

Network Working Group M. Crawford

Request for Comments: 2673 Fermilab

Category: Standards Track August 1999

Binary Labels in the Domain Name System

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 (1999). All Rights Reserved.

1. Introduction and Terminology

This document defines a "Bit-String Label" which may appear within

domain names. This new label type compactly represents a sequence of

"One-Bit Labels" and enables resource records to be stored at any

bit-boundary in a binary-named section of the domain name tree.

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


document are to be interpreted as described in [KWORD].

2. Motivation

Binary labels are intended to efficiently solve the problem of

storing data and delegating authority on arbitrary boundaries when

the structure of underlying name space is most naturally represented

in binary.

3. Label Format

Up to 256 One-Bit Labels can be grouped into a single Bit-String

Label. Within a Bit-String Label the most significant or "highest

level" bit appears first. This is unlike the ordering of DNS labels

themselves, which has the least significant or "lowest level" label

first. Nonetheless, this ordering seems to be the most natural and

efficient for representing binary labels.

Among consecutive Bit-String Labels, the bits in the first-appearing

label are less significant or "at a lower level" than the bits in

subsequent Bit-String Labels, just as ASCII labels are ordered.

3.1. Encoding

0 1 2

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 . . .


|0 1| ELT | Count | Label ... |


(Each tic mark represents one bit.)

ELT 000001 binary, the six-bit extended label type [EDNS0]

assigned to the Bit-String Label.

Count The number of significant bits in the Label field. A Count

value of zero indicates that 256 bits are significant.

(Thus the null label representing the DNS root cannot be

represented as a Bit String Label.)

Label The bit string representing a sequence of One-Bit Labels,

with the most significant bit first. That is, the One-Bit

Label in position 17 in the diagram above ...