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 primarily for the benefit of the operational area directors. Document editors and WG chairs should treat these comments just like any other last call comments.   I think the messages format and the mechanism for invoking DDT are very well written and very clear.   One question:   4.1 states LISP-DDT does not store actual EID-to- RLOC mappings; it is, rather, a distributed index that can be used to find the devices (Map Servers and their registered EIDs) that can be queried with LISP to obtain those mappings     If mapping in Map Servers are organized in a way that each Map Server maintains EIDs-RLOC mappings for a set of  VPNs or Tenants, then the Ingress node can use the VPN-ID or Tenant ID to find the desired MapServer. Under this circumstance, do you still need LISP-DDT?   It will be very helpful to have a paragraph describing what kind of environment will need LISP-DDT.   Thanks, Linda Dunbar