Re: ns delegation, unix dig vs dnsjava dig vs dnsjava Lookup

[Stefano B. <sou...@ba...>]

Brian Wellington ha scritto:
>> We use dnsjava to lookup MX records for SMTP delivery: what do you think
>> is the behavior required by DNS+SMTP specification? Currently we simply
>> run the Lookup using the dnsservers configured by the user (or the one
>> autodiscovered by dnsjava) and take its result as is. In this
>> "uudial.ch." domain and 194.246.118.118 configuration the dnsjava
>> "Lookup" does not return the MX record: is this intended? Should we do
>> something different? Can you answer this or give me a pointer to some
>> doc I can read about?
> 
> I don't know what 194.246.118.118 is, but when I query it, it's not
> doing recursion.  dnsjava's Lookup class is a stub resolver, so it
> should only be sending queries to servers that perform recursion.  If I
> instead send the query to a server that does perform recursion, I get
> the desired MX record.

Maybe I'm confusing iterative vs recursive terms.

I tried googling this but I didn't find an answer:

is a server allowed to reply non-recursively to a recursive question?

what does a client should (have to) do when a server replies without the
"ra" flag?

Should we keep resolving the data to the NS server received?

If so, can you suggest an approach to the problem using dnsjava?

Would this behavior be defined "iterative" resolution or iterative vs
recursive both describe only server side resolution?

What do other other clients do wrt non recursive servers?

Thank you again,
Stefano