[Pdns-users] Feedback on the recursor 3.0 requested + 3.0.1

bert hubert bert.hubert at netherlabs.nl
Fri May 5 07:34:56 UTC 2006

On Thu, May 04, 2006 at 06:16:20PM +0100, Stephen Harker wrote:
> noblemarine.co.uk.      10518   IN      MX      20
> bludger.positive-internet.com.
> noblemarine.co.uk.      68      IN      MX      10
> pop3.positive-internet.com.

Stephen, I spent quite some time pondering your setup. RFC 2181 says:

   Resource Records also have a time to live (TTL).  It is possible for
   the RRs in an RRSet to have different TTLs.  No uses for this have
   been found that cannot be better accomplished in other ways.  This
   can, however, cause partial replies (not marked "truncated") from a
   caching server, where the TTLs for some but not all the RRs in the
   RRSet have expired.

   Consequently the use of differing TTLs in an RRSet is hereby
   deprecated, the TTLs of all RRs in an RRSet must be the same.

So in a sense, you are feeding the internet bad data, and getting bad
results in return, which has an amount of fairness to it.

You are in luck though as the RFC tries to have its cake and eat it too:

   Should an authoritative source send such a malformed RRSet, the client
   should treat the RRs for all purposes as if all TTLs in the
   RRSet had been set to the value of the lowest TTL in the RRSet.

Implemented in http://wiki.powerdns.com/projects/trac/changeset/819

But you should still fix your broken ttls!


http://www.PowerDNS.com      Open source, database driven DNS Software 
http://netherlabs.nl              Open and Closed source services

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