>A top-level domain is one that has exactly one component, e.g., "com", >"org", "uk", or "tv". We also talk about suffixes, which would probably >include "co.uk", "k12.ca.us", and "edu.au". We mandate not querying the >top-level domains, since they can be algorithmically determined and we >really don't want to unnecessarily load the TLD servers. Not querying >suffixes is optional, as the definition for what a "suffix" is, because >there is no formal definition and this is really an optimization.
The abuse.net database lookup does an internal walk up the tree looking for an entry (in its own database, not the DNS), and I can report from experience that trying to track delegation point suffixes is an extremely hard problem. Things that look parallel often aren't, e.g., in the various state k12.xx.us domains, in some states there is one agency that serves all the schools so it's a real domain that should have a record, while in others it's just a label. And the list is highly dynamic, e.g., sakhalin.ru used to be a geographic label, similar to a lot of other <place>.ru domains, but now they have a municipal ISP and it has an MX record. R's, John _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
