I have reviewed this document as part of the Operational directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written with the intent of improving the operational aspects of the IETF drafts. Comments that are not addressed in last call may be included in AD reviews during the IESG review. Document editors and WG chairs should treat these comments just like any other last call comments. The draft defines the identifiers and challenges required to enable ACME to issue certificates for IP addresses. RFC8555 only defines challenges for DNS host names with identifier type "dns"; this document describes how challenges defined in the original ACME specification can be used to support validation of IPv4 and IPv6 addresses using identifier type "ip". The document also covers use of the TLS-ALPN challenge. The document is written clearly and ready to be advanced.