[Ietf-not43] contact lookups: the elephant in my room

[Eric A. Hall]

on 4/1/2003 12:16 PM Peter Gietz wrote:

> requirements on distributed search to something like:
> 
> "Contact lookup given a fully-qualified domain name or IP address"
> 
> where the server with the appropriate contact data of that domain could 
> be looked up via DNS SRV. That seems better to me than getting rid of a 
> MUST on contact lookup.

That's definitely the approach I favor, but like I said there are some
issues with this approach (despite these problems, I still favor this
approach however)

First of all, there is no global delegation body for contact identifiers.
This is in contrast to global delegations for resources such as DNS
domains, IP addresses, and ASNs. Since there is no global delegation body,
there is no existing delegation body which can be queried. As a result,
you either have to query a specific organization (the servers for .com or
.in-addr.arpa), or you have to query the end-nodes directly (asking the
servers for example.com for information about user at example.com).

Both of those approaches have the potential to result in incomplete answer
sets. In the case of asking the .com servers, you won't get information
about any delegations that user at example.com may have made under something
like .co.uk, and that database may also contain out-of-date or misleading
information (using user at example.com for some domains, goaway at example.com
for others, misdirection at hotmail.com for more, and so forth). Asking the
example.com servers may fail because the admin can choose not to provide
the information, or they may not even have any servers (in the latter
case, you would end up falling back to .com servers, and facing those
problems). So no matter what path you choose you are only going to get the
information that people want you to have; asking their servers directly at
least gives you a mechanism to aks for the information that they *want*
you to have, with a fallback to limited information. A catalog server will
be able to collate information from various pools, but again, this will
only work to the point where the data is timely and accurate, and there
are too many hurdles to deploy a catalog approach as the standard.

Probably the ultimate solution here is to have some kind of global body
delegate global contact identifiers, with other delegation bodies
requiring an identifier before any delegations can be made, and with the
identifier database being updated whenever a delegation is made. It would
be easy to stick a WHOIS-like front-end on that. I don't think anybody
expects that this would happen any time soon though, and I hesitate to
even suggest this because I don't want folks to think I'm advocating it
(to be clear, I'm not).

My preference would be to use a bottom-up query against an email address
as the "standard" method, with the assumption that ad-hoc catalog servers
will emerge to provide "global" interfaces which address the actual need.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/