Elkins 26241 USA WV tjw.ietf@gmail.com

Application DBOUND2 Internet clients attempt to make inferences about the administrative relationship based on domain names. Currently it is not possible to confirm organizational boundaries in the DNS. Current mitigation strategies have there own issues. This memo attempts to outline these issues.

Introduction Working off of the earlier problem statement , which we still consider valid.

Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here. DNS terminology is as described in .

Normative References Informative References

Previous Use Cases The use cases which involve use of the public suffix list, summarized from the initial problem statement:

• HTTP State management cookies
• User interface indicators
• Setting the document.domain property
• Email authentication mechanisms
• SSL and TLS certificates
• HSTS and Public Key Pinning
• Linking domains together

While all of these are very important to solve, part of the issue with the first attempt to address this was overreaching goals. The suggestion is to initially limit the list to a subset, such as these:

• HTTP State management cookies
• SSL and TLS certificates
• HSTS and Public Key Pinning

Replicating the Public Suffix List A main topic that immediately arises from this discussion is the replacement of the Public Suffix List (PSL). What does need to be quantified and understood is the 1) workload needed to update the PSL; 2) how much time is involved with technical escalations; and 3) the quality of the existing data in the PSL. Creating an IANA registry to track such changes could incur a large workload demand upon IANA staff, and this will need to be understood.

Solution Space is a Problem Space The problem requires solutions which are both static lists and DNS zone data that can be enumerated. Both must be addressed in understanding the problem.

Security Considerations None at this time.

IANA Considerations None at this time.

Acknowledgements The author leans heavily on the initial problem statement and thanks Andrew Sullivan, John Levine, Murray Kucherawy and Paul Vixie for comments and suggestions.

Appendix

Acknowledgements