[Pdns-users] Problem with PowerDNS Recursor 3.2 and EDNS enabled

[bert hubert]

On Thu, Apr 01, 2010 at 12:09:12PM +0200, Detlef Peeters wrote:
> Hello,
> 
> I've installed yesterday the Update to PowerDNS Recursor 3.2. In the
> config I've enabled EDNS with the option "disable-edns=no".

Detlef,

You've discovered the (removed) EDNS support from PowerDNS. By mistake,
'disable-edns' was not removed from the --help output.

It is not documented, and it is is not supported (for now). The disable-edns
feature should not have been visible.

That it works at all is a miracle ;-)

> When we try to reach "www.danskebank.dk" then there is no resolution to
> the IP. In the log I can see following entrys:
> 
> pdns_recursor[3518]: Discarding unexpected packet from 192.42.93.33: , 0
> pdns_recursor[3518]: Discarding unexpected packet from 192.35.51.33: , 0
> pdns_recursor[3518]: Discarding unexpected packet from 192.41.162.33: , 0
> pdns_recursor[3518]: Discarding unexpected packet from 192.5.6.33: , 0

EDNS support was disabled for this specific reason. It turns out that as a
nameserver, an inordinate amount of time and packets is spent on discovering
the sizeable number of servers that do not support EDNS, and in fact return
strange error packets.

> Where is the problem? With the nameserver from Danskbank? Or is it better
> at the moment to disable EDNS in PowerDNS Recursor?

Definitely.

In the future, we might move to 'EDNS if really necessary', for example,
after receiving a truncated packet.

	Bert