[Pdns-users] How can I enforce additional TXT records in DNS response?

Matthias Kruzenski matthias.kruzenski1 at gmail.com
Wed Jan 15 21:01:15 UTC 2020

The reason is as follows:

I work for a telecommunications company. This company provides customers
with products such as MNP and HLR lookups. A NAPTR query is used to check
whether a mobile number has been ported (MNP) or in which net / country the
number is currently logged on (HLR).

The company is currently using a self-programmed DNS server. This does
exactly what I have described, it parses the NAPTR query and answers with a
NAPTR record as well as an additional TXT record.

Since this involves millions of queries every day, overhead like SOA
queries are absolutely undesirable because if a SOA query has to be
answered first and then an ANY query, then 2 co-processes are necessary in
the case of the pipe backend. It could be done with only one co-process if
only the parsed NAPTR question would be passed to the backend since only
that was requested by the client. Most important is the performance and
number of questions answered. It does not matter whether this answer is
authoritative or not.

So it would be great if PowerDNS could be configured to do exactly the same
thing as the self-programmed company DNS Server: Parse the NAPTR query,
pass it to the backend, send the answer from the backend to the client, no
matter how this answer looks like. The company has a reason to have an
additional TXT record in the answer.

If that's impossible, that's ok, then we have to look for another solution
that meets our requirements. I just don't know if it's possible and how, I
could not find an answer for this problem in the docs.

Am Mi., 15. Jan. 2020 um 20:38 Uhr schrieb Jan-Piet Mens <list at mens.de>:

> (summarizing from two of your messages)
> > I only want to pass what was explicitly requested to the backend and
> > nothing else because the server has to process many millions of
> > requests and any overhead is not desired.
> >I want PowerDNS to send exactly the records to the client that the pipe
> >backend produced. Nothing should be left out.
> That seems contradictory to me.
> Be that as it may, the client issues a query for a particular type (e.g
> TXT or AAAA);  even if PowerDNS returned all types it has for a qname to
> the client which, as you've noticed it doesn't, the latter would likely
> not use the result.
>         -JP
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