Internet-Draft Special-Use Domain Names Registry October 2022
Hoffman Expires 6 April 2023 [Page]
Network Working Group
6761 (if approved)
1918, 2606 (if approved)
Intended Status:
Standards Track
P. Hoffman

Special-Use Domain Names Registry


This document obsoletes RFC 6761 that created the Special-Use Domain Names registry at IANA for domain names that are reserved for special use. The registry has proved to be useful. RFC 6761 also has a description for when reserving such a name is appropriate, and the procedure for doing so; those descriptions have turned out to cause many problems in the IETF. Because of those problems, this document obsoletes RFC 6761 while retaining the registry and greatly reducing the rest of the discussion and requirements in RFC 6761. It places the responsibility for accepting Special-Use Domain Names entries with the IESG.

[ A repository for this draft can be found here. ]

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 6 April 2023.

Table of Contents

1. Introduction

There is a long history of RFCs that reserve some domain names for private use. [RFC2606] reserved ".test", ".example", ".invalid", ".localhost", "", "", and "", as well as all names below those names. It also created a registry at IANA called "special-use domain names" for those names and for future names assigned by the IETF.

This document obsoletes [RFC6761]. It keeps the IANA registry and all its contents, but removes some of the requirements from RFC 6761 that were sometimes ignored after RFC 6761 was published. It also has a brief discussion of what has happened since RFC 6761 was published. The intentions for these changes to RFC 6761 are to make it easier for the IESG to analyze proposals for inclusion in the registry, and to make the requirements match what the IESG is already doing.

In this document, "domain name" means a name in the global DNS as defined in [RFC8499].

2. Requirements for the Special-Use Domain Names Registry

In order to be added to the Special-Use Domain Names registry, a domain name needs to be specified in an IETF "Standards Action" RFC or an "IESG Approval" specification. These terms are defined in [RFC8126] as:

Standards Action:

For the Standards Action policy, values are assigned only through Standards Track or Best Current Practice RFCs in the IETF Stream.

IESG Approval:

New assignments may be approved by the IESG. Although there is no requirement that the request be documented in an RFC, the IESG has the discretion to request documents or other supporting materials on a case-by-case basis.

A specification for this registry does not need to be an RFC.

RFC 6761 said that its process applied when a name required special handling in order to implement some desired new functionality. This document drops that requirement and the associated requirements for documenting all the types of special handling required.

Of course, the IESG should require that all use case assumptions and requirements for the names added to the registry be wholly contained in the RFC or specification defining that name. However, the level of that requirement is controlled by the IESG for each name, not by this document. It is the IESG that decide whether to add new names that are top-level names (such as ".example"), or names at the second level of existing Special Domains (such as "").

3. History of the Special-Use Domain Names Registry

RFC 6761 contained the initial entries for the registry. Those were the names from [RFC2606] as well as "" names for the private IPv4 addresses in [RFC1918]: 10/8, 172.16/12, and 192.168/16.

Immediately after RFC 6761 was published, [RFC6762] was published and contained entries for "", "", "", "", and "". It also contained the registration for ".local". All of these were placed in the Special-Use Domain Names registry.

After that, the registry became contentious, with many parties asking to have top-level names that were related to their protocols added to the registry. In September 2014, the IAB issued a liaison statment to ICANN concerning the registry. That statement said in part:

Under its current charter, the DNSOP working group in the IETF is responsible to review and clarify the overlap between (among other things) the special names registry from RFC 6761 and the public DNS root. This could include consideration of the problem of existing name collisions, provision of additional guidelines, or further modification to the process in RFC 6761 to reduce the potential for collisions in the future.

In September 2015, the IETF published a blog post, It says in part:

...the IESG believes RFC 6761 needs action, and substantial community input. It needs to be open for review and modification because the current process is unscalable.

Soon after, only one name, ".onion" [RFC7686] from October 2015, was added to the registry.

Even with a great deal of subsequent effort, the DNSOP Working Group could not reach consensus on how to move forward with any names other than ".onion". After that, the only names added to the registry were six names under ".arpa". Of those, only one RFC specifying those names followed the requirements in RFC 6761 for documenting all the types of special handling required.

In the future, the DNSOP WG and IESG can consider amending the DNSOP Working Group charter to remove the responsibility of the DNSOP WG for special-use domain names.

4. IANA Considerations

All entries in the Special-Use Domain Names registry that refer to RFC 6761 are updated to point to this document.

Names can be added to this registry by the IETF after being specified in an IETF "Standards Action" RFC or an "IESG Approval" specification.

The requirement from RFC 6761 that the specification must contain "Domain Name Reservation Considerations" is no longer required. It has not been consistently enforced by the IETF and IANA since 2015.

5. Security Considerations

This document has the same security considerations as those expressed in RFC 6761:

This document outlines the circumstances in which reserving a domain name for special use is appropriate, and the procedure for having that Special-Use Domain Name recorded by IANA. Any document requesting such a Special-Use Domain Name needs to contain an appropriate "Security Considerations" section which describes any security issues relevant to that special use.

6. References

6.1. Normative References

Cheshire, S. and M. Krochmal, "Special-Use Domain Names", RFC 6761, DOI 10.17487/RFC6761, , <>.
Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, , <>.
Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, , <>.

6.2. Informative References

Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. J., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918, , <>.
Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS Names", BCP 32, RFC 2606, DOI 10.17487/RFC2606, , <>.
Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, DOI 10.17487/RFC6762, , <>.
Appelbaum, J. and A. Muffett, "The ".onion" Special-Use Domain Name", RFC 7686, DOI 10.17487/RFC7686, , <>.

Appendix A. Acknowledgements

This document lifts many ideas from RFC 6761. Stuart Cheshire and Marc Krochmal deserve acknowledgement for the writing and the hard work that went into getting RFC 6761 through the IETF process. The members of the DNSOP Working Group who participated in the follow-up work on the registry also deserve acknowledgement.

Author's Address

Paul Hoffman