I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the security area directors.  Document editors and WG chairs should treat these comments just like any other last call comments. Overview A6 was a proposed replacement for AAAA records. A6 has not achieved the anticipated level of support or provided the anticipated benefits in practice. This draft moves A6 to historic, deprecating use of A6 records. Comments: Removing A6 removes a potential source of inconsistency and thus improves consistency.  One possible consequence of this particular change is that information that was previously expressible via the A6 mechanism will no longer be visible. While this is not necessarily good or bad from a security standpoint it is an issue that should be mentioned in the Security Considerations. Another possible security impact is that it will not be possible to divide up administrative duties in the manner originally envisaged in the A6 proposal. While it is far from clear that this division is useful (or achievable) it should probably be noted. In particular it will not be possible to achieve renumbering of whole domains by changing one record. It is quite possible that some domains will continue to employ A6 domains as an administrative convenience, generating the corresponding AAAA records as required. This case needs more consideration from a security point of view. It would be useful to require that such records be ignored by applications and preferably be blocked from external view. -- Website: http://hallambaker.com/