Hello,

I hope this is the right list for my question.
(the implemnetation in question is closed source and
no mailing list exists for it. I need "quality input"
on the issue to send to the manufacturer so that they
will implement their "DNS server implementation" as
correct as possible.)
Maybe it would also make sense to put the information
asked here in a "best practice" document on the issue
of devices implementing such "stub DNS server implementation".

----

Many load balancers implement some DNS functionality,
but their implementation is very limited.

Example:
www.example.com gets delegated to lb1.example.com and
lb2.example.com, which are load balancers.

In Zone file terms:
www.example.com.                IN      NS      lb1.example.com.
www.example.com.                IN      NS      lb2.example.com.

In therory the load balancer should have a "zone" for
www.example.com with SOA records, NS records etc.

However they typically just implement A records
(maybe some exist which also can serve A6 or AAAA records)

Now to the question:
How should the load balancer react to queries?

To most of the queries the load balancer must send back
"empty answers". It sends back the question with the
flags corrected, an empty answer, authoritative,
and additional section.

How should it react "correctly" to queries for NS entries
and SOA entries? (These RR types are and will NOT
be implemented on the load balancer)

Should it send back NOTIMP (NOTIMPL in Bind) answers?
Or should it also send back empty answers?

I assume, a solution which sends back "REFUSED" to a
query will be wrong for any type of query.

What should be sent back for other classes (like CHAOS)?
empty answers, NOTIMP answer or anything else?
(REFUSED should be ok in this case)

The load balancers also don't implement ANY '*' queries.
Am I right to assume that 'NOTIMP' would be the right answer?


Thanks for any Input on the issue.


Kind regards

Guido Roeskens
Swisscom Fixnet AG
Bluewin
.
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