Hi, 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. Overall, the document is very straightforward and the Security Considerations section is appropriate for the content. I do have one nit to pass along. I think that a paragraph break is in the wrong place in the Introduction. Current in Introduction: (end of first paragraph) manner which is efficient, scalable and straightforward to implement. For IPv4, some networks configure RTBH installations using [RFC1918] address space or the address blocks reserved for documentation in [RFC5737]. However RTBH configurations are not documentation, but operationally important features of many public-facing production networks. Furthermore, [RFC3849] specifies that the IPv6 documentation prefix should be filtered in both local and public contexts. On this basis, it is suggested that both private network address blocks and documentation prefixes described in [RFC5737] are inappropriate for the purpose of RTBH configurations. Suggested: manner which is efficient, scalable and straightforward to implement. For IPv4, some networks configure RTBH installations using [RFC1918] address space or the address blocks reserved for documentation in [RFC5737]. However RTBH configurations are not documentation, but operationally important features of many public-facing production networks. Furthermore, [RFC3849] specifies that the IPv6 documentation prefix should be filtered in both local and public contexts. On this basis, it is suggested that both private network address blocks and documentation prefixes described in [RFC5737] are inappropriate for the purpose of RTBH configurations. Regards, Chris