dnsop O. Sury
Internet-Draft E. Hunt
Updates: 1035,3597,4035 (if approved) Internet Systems Consortium
Intended status: Standards Track May 13, 2019
Expires: November 14, 2019
Deprecating obsolete DNS Resource Records Types
draft-sury-deprecate-obsolete-resource-records-01
Abstract
This document deprecates Resource Records (RR) Types that are either
not being used for anything meaningful or were been already made
obsolete by other RFCs. This document updates [RFC1035], [RFC1035],
[RFC4034].
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Deprecating MD, MF, MB, MG, MR, MINFO, MAILA, and MAILBRR
Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 2
4. Implementation Considerations . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. Operational Considerations . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . 4
8.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
[RFC1035] and other documents have defined some Resource Record (RR)
Types that are no longer in common use, some of which have been
rendered obsolete by subsequent standards, but have never been
clearly deprecated in the context of the DNS. In some cases there
have been interoperability problems between DNS implementations that
support these types and those that do not - for example, because of
DNS name compression in the wire format. Continued support for these
RR Types imposes a complexity cost on new implementations for little
benefit.
This document formally deprecates such RR Types, allowing
implementations to drop specific support for them.
2. Deprecating MD, MF, MB, MG, MR, MINFO, MAILA, and MAILBRR Types
The MD, MF, MB, MG, MR, MINFO, MAILA, and MAILB RR Types aren't used
in any existing standards, and this documents deprecates their usage.
The MD, MF, MB, MG, MR, and MINFO RR Types RDATA contain a domain
name that could be compressed in the RDATA section.
As an update to [RFC3597] and [RFC4034] this document specifies that
for MD, MF, MB, MG, MR, and MINFO RR types, the canonical form is
such that no downcasing of embedded domain names takes place, and is
otherwise identical to the canonical form specified in [RFC4034]
section 6.2.
3. IANA Considerations
This documents updates the IANA registry "Domain Name System (DNS)
Parameters" ([DNS-IANA]).
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+-------+-------+------------+---------------+
| TYPE | Value | Meaning | Reference |
+-------+-------+------------+---------------+
| MD | 3 | DEPRECATED | This document |
| MF | 4 | DEPRECATED | This document |
| MB | 7 | DEPRECATED | This document |
| MG | 8 | DEPRECATED | This document |
| MR | 9 | DEPRECATED | This document |
| MINFO | 14 | DEPRECATED | This document |
+-------+-------+------------+---------------+
4. Implementation Considerations
Types will be flagged as obsolete/deprecated in the IANA registry,
and the following guidance is given to DNS implementors in the
handling of obsolete/deprecated RR types:
1. Authoritative DNS Servers SHOULD issue a warning when loading
zones that contain DEPRECATED RR Types;
2. DNS Servers MUST NOT compress RDATA when rendering DEPRECATED RR
Types to wire format;
3. Recursive DNS Servers MAY support legacy compression in
DEPRECATED RR Types for received data for backward compatibility
if desired, but SHOULD warn if such information is received.
Compressed RDATA in DEPRECATED RR Types MUST be uncompressed
before sending and they MUST NOT be re-transmitted;
4. DNS Clients which receive DEPRECATED RR Types MAY interpret them
as unknown RR types ([RFC3597]), and MUST NOT interfere with
their transmission;
5. DNSSEC Validators and Signers SHOULD treat RDATA for DEPRECATED
RR Types as opaque with respect to canonical RR ordering and
deduplication;
6. DEPRECATED RR Types MUST never be treated as a known-type with
respect to the wire protocol.
5. Security Considerations
This document has no security considerations.
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6. Operational Considerations
The varying states of implementation of MD, MF, MB, MG, MR, and MINFO
RR Types has already caused operational problems between DNS
implementations that do implement the aforementioned types and those
that don't because of DNS compression on the wire. This document
aims to rectify the situation by encouraging removal of support for
all these RR types in DNS implementations. This should not cause
signficant operational problems because these records are not in wide
use on the Internet. [COMMENT: Some data?]
7. Acknowledgements
Peter van Dijk for poking me to write the draft. Daniel Salzman for
reviewing the document. Evan Hunt and Michael Casadevall to write
Implementation Considerations section.
8. References
8.1. Normative References
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record
(RR) Types", RFC 3597, DOI 10.17487/RFC3597, September
2003, <https://www.rfc-editor.org/info/rfc3597>.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, DOI 10.17487/RFC4034, March 2005,
<https://www.rfc-editor.org/info/rfc4034>.
8.2. Informative References
[DNS-IANA]
"Domain Name System (DNS) Parameters",
<https://www.iana.org/assignments/dns-parameters/
dns-parameters.xhtml>.
Authors' Addresses
Ondrej Sury
Internet Systems Consortium
CZ
EMail: ondrej@isc.org
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Evan Hunt
Internet Systems Consortium
US
EMail: each@isc.org
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