[Pdns-users] qtype argument to pipe backend is always set to 'ANY' (continued)

Sudarshan Raghavan sudarshan.t.raghavan at gmail.com
Thu Feb 4 09:12:13 UTC 2010

Sorry, should have sent it to the list.

On Thu, Feb 4, 2010 at 2:41 PM, Sudarshan Raghavan
<sudarshan.t.raghavan at gmail.com> wrote:
> Thanks for the explanation. Consider the scenario where a client wants
> to get the NS records for a domain and is not interested in any MX
> records that are available for this domain. How is the backed supposed
> to know this if 'ANY' is passed? We will end up returning the NS and
> MX records in this case.
> I am assuming the answer to this question would be it does not hurt to
> send out the MX records in the response. The client gets the
> information it wants and the extra stuff will be useful for any
> intermediate dns caches. Is my understanding correct?
> Regards,
> Sudarshan
> On Thu, Feb 4, 2010 at 1:59 PM, bert hubert <bert.hubert at netherlabs.nl> wrote:
>> This question keeps getting asked, I've put a note about this in the
>> documentation, http://doc.powerdns.com/backends-detail.html#AEN5622
>> For completeness:
>> Besides regular query types, the DNS also knows the 'ANY' query type. When
>> a server receives a question for this ANY type, it should reply with all
>> record types available.
>> Backends should therefore implement being able to answer 'ANY' queries in
>> this way, and supply all record types they have when they receive such an
>> 'ANY' query. This is reflected in the sample script above, which for every
>> qtype answers if the type matches, or if the query is for 'ANY'.
>> However, since backends need to implement the ANY query anyhow, PowerDNS
>> makes use of this. Since almost all DNS queries internally need to be
>> translated first into a CNAME query and then into the actual query, possibly
>> followed by a SOA or NS query (this is how DNS works internally), it makes
>> sense for PowerDNS to speed this up, and just ask the ANY query of a
>> backend.
>> When it has done so, it gets the data about SOA, CNAME and NS records in one
>> go. This speeds things up tremendously.
>> The upshot of the above is that for any backend, including the PIPE backend,
>> implementing the ANY query is NOT optional. And in fact, a backend may see
>> almost exclusively ANY queries. This is not a bug.
>> On Thu, Feb 04, 2010 at 12:05:08PM +0530, Sudarshan Raghavan wrote:
>>> I have tried this on both 2.9.21 and 2.9.22 versions. Should I compile
>>> any extra module to get this working?
>>> Sorry for starting a separate thread. For some reason I did not
>>> receive my own post (I have that profile option enabled) and I was not
>>> able to find a way to reply from the web interface.
>>> Regards,
>>> Sudarshan
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