Question about (negative) caching

["Philip A. Prindeville" <philipp@mirapoint.com>]

I was wondering if the caching code (which I suppose I should
look through one of these days) supports negative caching or
if negative caching even makes sense in the context of LDAP.

I remember a few years ago a site was being accidentally
mailbombed to a non-existent machine in their domain.  They
had a *.dom.ain mail record pointing to their clearing house,
and which then queried the name server (an underpowered
MicroVAX-II) about nosuchmachine.dom.ain repeatedly,
finally bringing the name server machine to its knees (do
machines have knees?).

I imagine something similar might happen in LDAP.  In such
a case, it would be useful for a caching client to remember
that user, group, or machine didn't exist.  The question is for
how long?  Would the standard TTL apply?  And how would
you know the TTL given that you didn't get back any data?

I'm new to this list so if the question when to the wrong
forum, "milles excuses d'avance."

-Philip