[Pdns-users] Enhancing pdns recursor observability

Peter van Dijk peter.van.dijk at netherlabs.nl
Mon May 13 14:49:45 UTC 2013

Hello Thomas,

On May 13, 2013, at 12:11 , Thomas Mieslinger wrote:

> To be able to understand these problems in a live system I would like to have some sort of tracing facility in pdns_recursor which can be turned on and off without restarting the service.
> Ideally pdns_recursor would provide some sort of cli which can be used to create output channels, create, list and delete filters.

Have you seen 3.5s trace-regex?

[vagrant at pdns ~/pdns/pdns (master)⚡]$ sudo ./rec_control trace-regex '95\.194\.in-addr\.arpa'
[vagrant at pdns ~/pdns/pdns (master)⚡]$ dig -x
... answer follows

meanwhile on my recursor (running in a terminal, in the foreground):
May 13 16:44:59 0 [23] question for '|PTR' from
May 13 16:45:00 [23] Looking for CNAME cache hit of '|CNAME'
May 13 16:45:00 [23] No CNAME cache hit of '|CNAME' found
May 13 16:45:00 [23] No cache hit for '|PTR', trying to find an appropriate NS record
... 830 more lines of debugging
May 13 16:46:51 [1]  2.0- status=got results, this level of recursion done

> Has anyone else sometimes the need to dive deeply into how the recursor is working and which server in the outside world are failing?

Yes, this is a very real need. We always welcome suggestions for improving the recursor in this area.

> Is this idea worth opening a wishlist ticket?

Your idea is very big, and it is hard to say whether it would get picked up as a whole. If you can split it up, perhaps pointing out specific things you miss in our current trace(-regex) functionality, this would help us improve the recursor in smaller steps.

I like your idea, though!

Kind regards,
Peter van Dijk
Netherlabs Computer Consulting BV - http://www.netherlabs.nl/

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