[Pdns-users] recursor fail to resolve

Sergio Cesar sergio at winc.net
Fri May 1 17:09:22 UTC 2020

Thank you for the reply.

Here it is, not sure what that means.
The recursor is running on the same server as the PDNS with a different 
IP address.  if that makes a difference.

root at ns1:~# rec_control trace-regex s-s.mx

On 5/1/2020 11:37 AM, Aki Tuomi wrote:
>> On 05/01/2020 6:31 PM Sergio P Cesar via Pdns-users <pdns-users at mailman.powerdns.com> wrote:
>> I am new with pdns, just installed a resolver 4.3.0-rc2 to learn and all
>> seems to work but stumbled into an issue I cant resolve.
>> My mailserver failed to deliver email to a few domains, in tracking it I
>> found that their DNS will drop the first packet on every new query  but
>> will respond on a second query ok and every one after that. (5 minutes
>> timeout) it will drop the 1st packet again.
>> I was expecting the recursor to query the 2nd and 3rd server in their
>> list but it does not look like it is doing that.
>> It seems like it is caching the failure and does not query again at all
>> for a while.
>> I changed packetcache-servfail-ttl=0 and now it looks like after the 3rd
>> query attempt it will work as the far end server now respond.
>> Not sure this is correct setting  or I will have adverse effect setting
>> this to 0.
>> Perhaps I have not set something else that will tell the recursor to try
>> the next server if the first one fail to respond or send a second packet
>> or a retry.
>> I used bind to test and it gets a response on the first try. I did not
>> try to trace the packets from a bind query.
>> Thanks
> Try `rec_control trace-regex domain.com` and post that. Without censoring the results.
> Aki

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