[Pdns-dev] A & CNAME

David Saez eslist at ols.es
Wed Jan 4 12:31:18 CET 2012


so, for every request, powerdns does not a CNAME databse lookup and then 
a A database
lookup if it did notr find the CNAME record, right ?

if this is true and your zones contain more A records than CNAME records 
, then most of
the CNAME databse lookups are useless (and take valuable resources), for 
those cases
it's possible to save those lookups by:

a) first do the A lookup and the then CNAME lookup


b) allow hostnames in the A record and when found return a CNAME

> Hello David,
> On Dec 29, 2011, at 12:10 , David Saez wrote:
>> Not sure if this has been requested before (mainly because i
>> could not find a proper way to search all the mailing list archives)
>> but it will be great to be able to server A/CNAME records using
>> less backend queries. For what i read it seems that for A requests
>> CNAME is tried first (unless skip-cname=on) but at least in my case
>> and probably this is the general situation, we have much more A
>> records than CNAMEs and never have a A and CNAME for the same
>> hostname , so it will be good to have some option so PowerDNS first
>> tries A records and if not found then tries CNAMEs, this will save
>> a lot of queries. Another way will be to allow A database records to point to hostnames instead to ip addresses and then have PowerDNS
>> convert this database A records into CNAME answers, so we can have totallty avoid the need for the CNAME query (skip-cname=on) but still
>> be able to serve CNAME records
> As it turns out, skip-cname does not actually do anything in the current version of PowerDNS. However, I'm not sure it would apply to your issue anyway. PowerDNS does not do separate CNAME queries and skip-cname never was about skipping an initial query.
> Note that having A and CNAME for the same name is a misconfiguration.
> I hope this helps; let me know if you have more questions.
> Kind regards,
> Peter van Dijk
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