Strange ns answers...

[Rodney Joffe]

Kevin Darcy wrote:
> 
> Rodney Joffe wrote:
> > But RFC 2870 *is* strictly adhered to by all the ?.root-servers.net and
> > ?.gtld-servers.net. Which is what counts here.
> 
> If it's being strictly adhered to, how can a root slave also be a net slave or a com slave?

The historical significance can be ignored for a. and
g.root-servers.net. Disingenuous question ;-)

> 
> I'm now starting to lean more towards "single
> machine, inconsistent Additional sections" rather than multiple machines. Which is rather bizarre.
> Maybe it's "trimming" the responses based on dynamically-updated link-level-utilization metrics (???)

Huh? 

Anyway, that is one "puzzlement" that perhaps ISC or nominum may be
interested in?

> 
> This pair of queries isn't nearly as strange as what you showed before. It's quite common for a
> recursive nameserver to return a partial (or empty) Additional section on the first query, and then a
> full one on the next, because the answer to the "fetch-glue" query may have arrived in the interim.

Correct. And as we now know, that action is absolutely predictable,
notwithstanding the strangeness above. Glue records are always present
and returned on the first query to the root for authoritative
nameservers contained within the same parent zone. They are never
returned by the root for "foreign" authoritative nameservers in the
first query assuming the cache is empty, and fetch-glue takes place.
However, that predictability then confirms my hypothesis. It can be a
problem to have authoritative nameservers outside the parent zone. I
don't ever recall seeing that in a bind how-to or faq so I appreciate
the education. 

> > This would indicate that it can be detrimental to use nameservers that
> > are outside the domain's Tree/Parent/Zone etc. especially if the "in
> > zone" nameserver is unreachable.
> 
> Detrimental only if you use bizarro nameservers like 4.2.2.1 :-)

Nothing to do with that ;-) 4.2.2.1 is a recursive server.  For a fully
functioning recursive server, it is the lack of glue in the root that
causes the problem.

I guess we agree and the subject is now beaten to death :-)
-- 
Rodney Joffe
CenterGate Research Group, LLC.
http://www.centergate.com
"Technology so advanced, even we don't understand it!"(SM)