Strange ns answers...

[Rodney Joffe]

Kevin Darcy wrote:
> 
> This is probably some sort of  are actually answering your queries at different times. Normal?
> No. Legal? Sure.

As it turns out, it has nothing to do with clustering/load balancing
setup and different name servers

I've done some digging (pardon the pun) on my own in the absence of a
response from the usual suspects on namedroppers. It seems to be related
to RFC 2870.

It appears that RFC 2870 (BCP) suggests that roots not fetch glue
records for queries, or perform any recursive services. 

Specifically... RFC 2870:  Root Name Server Operational Requirements. R.
Bush, D. Karrenberg, M. Kosters, R. Plzak. June 2000. (Format: TXT=21133
bytes) (Obsoletes RFC2010) (Also BCP0040) (Status: BEST CURRENT
PRACTICE)
 
"2.5 Servers MUST provide authoritative responses only from the zones
they serve. The servers MUST disable recursive lookup, forwarding, or
any other function that may allow them to provide cached answers. They
also MUST NOT provide secondary service for any zones other than the
root and root-servers.net zones. These restrictions help prevent undue
load on the root servers and reduce the chance of their caching
incorrect data."

This effectively means that for any domain that has an authoritative
name server in another zone, the glue records must be fetched by your
recursive server. I guess it makes sense, and obviously the authors have
extensive experience with the load effects.

My assumption, therefore, is that it is imperative that authoritative
name servers should *always* be part of the same zone as the domain they
answer for, because it is only in these cases that all the glue is
present in the root. If any of the authoritative name servers belong to
a different zone, a delay in lookup will always occur as the user's
recursive server walks the try to fetch the glue.

The only alternative is for the glue to be stored in the root, but I see
how that can lead to stale data.

On the other hand, I may be totally wrong. In which case I'd love to
learn.

-- 
Rodney Joffe
CenterGate Research Group, LLC.
http://www.centergate.com
"Technology so advanced, even we don't understand it!"(SM)