The Role of Wildcards in the Domain Name System
RFC 4592
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Document |
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RFC - Proposed Standard
(July 2006; Errata)
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Author |
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Edward Lewis
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Last updated |
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2015-10-14
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IETF
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plain text
html
pdf
htmlized
bibtex
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Stream |
WG state
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(None)
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Document shepherd |
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No shepherd assigned
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IESG |
IESG state |
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RFC 4592 (Proposed Standard)
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Consensus Boilerplate |
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Unknown
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Telechat date |
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Responsible AD |
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Margaret Cullen
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Send notices to |
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olaf@nlnetlabs.nl
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Network Working Group E. Lewis
Request for Comments: 4592 NeuStar
Updates: 1034, 2672 July 2006
Category: Standards Track
The Role of Wildcards
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 (2006).
Abstract
This is an update to the wildcard definition of RFC 1034. The
interaction with wildcards and CNAME is changed, an error condition
is removed, and the words defining some concepts central to wildcards
are changed. The overall goal is not to change wildcards, but to
refine the definition of RFC 1034.
Lewis Standards Track [Page 1]
RFC 4592 DNSEXT WCARD July 2006
Table of Contents
1. Introduction ....................................................3
1.1. Motivation .................................................3
1.2. The Original Definition ....................................3
1.3. Roadmap to This Document ...................................4
1.3.1. New Terms ...........................................5
1.3.2. Changed Text ........................................5
1.3.3. Considerations with Special Types ...................5
1.4. Standards Terminology ......................................6
2. Wildcard Syntax .................................................6
2.1. Identifying a Wildcard .....................................6
2.1.1. Wildcard Domain Name and Asterisk Label .............6
2.1.2. Asterisks and Other Characters ......................7
2.1.3. Non-terminal Wildcard Domain Names ..................7
2.2. Existence Rules ............................................7
2.2.1. An Example ..........................................8
2.2.2. Empty Non-terminals .................................9
2.2.3. Yet Another Definition of Existence ................10
2.3. When Is a Wildcard Domain Name Not Special? ...............10
3. Impact of a Wildcard Domain Name on a Response .................10
3.1. Step 2 ....................................................11
3.2. Step 3 ....................................................11
3.3. Part 'c' ..................................................12
3.3.1. Closest Encloser and the Source of Synthesis .......12
3.3.2. Closest Encloser and Source of Synthesis Examples ..13
3.3.3. Type Matching ......................................13
4. Considerations with Special Types ..............................14
4.1. SOA RRSet at a Wildcard Domain Name .......................14
4.2. NS RRSet at a Wildcard Domain Name ........................14
4.2.1. Discarded Notions ..................................15
4.3. CNAME RRSet at a Wildcard Domain Name .....................16
4.4. DNAME RRSet at a Wildcard Domain Name .....................16
4.5. SRV RRSet at a Wildcard Domain Name .......................17
4.6. DS RRSet at a Wildcard Domain Name ........................17
4.7. NSEC RRSet at a Wildcard Domain Name ......................18
4.8. RRSIG at a Wildcard Domain Name ...........................18
4.9. Empty Non-terminal Wildcard Domain Name ...................18
5. Security Considerations ........................................18
6. References .....................................................18
6.1. Normative References ......................................18
6.2. Informative References ....................................19
7. Others Contributing to the Document ............................19
Lewis Standards Track [Page 2]
RFC 4592 DNSEXT WCARD July 2006
1. Introduction
In RFC 1034 [RFC1034], sections 4.3.2 and 4.3.3 describe the
synthesis of answers from special resource records (RRs) called
wildcards. The definition in RFC 1034 is incomplete and has proven
to be confusing. This document describes the wildcard synthesis by
adding to the discussion and making limited modifications.
Modifications are made to close inconsistencies that have led to
interoperability issues. This description does not expand the
service intended by the original definition.
Staying within the spirit and style of the original documents, this
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