[Pdns-users] pdns-recursor returning bad data intermittently

Thu Feb 4 18:31:32 UTC 2010

Hi, I am pasting some info on what version we're running below along
with the config files for your reference. We're seeing some intermittent
issues with our installation where the pdns-recursor is returning wrong
data. The last time this happened I dumped the cache and saw that one of
the 2 pdns-recursor processes had incorrect data cached. 

### good data ###
# grep -i smtp.mydomain.net pdns.cachedump.6020
231.23.17.172.in-addr.arpa. 72819 IN PTR smtp.mydomain.net.
smtp.mydomain.net. 80067 IN SOA localhost. root. 1 604800 86400 2419200
604800
smtp.mydomain.net. 65669 IN A 172.17.23.231

### bad data ###
# grep -i smtp.mydomain.net pdns.cachedump.6021
231.23.17.172.in-addr.arpa. 80279 IN PTR smtp.mydomain.net.
smtp.mydomain.net. 856 IN A 172.16.1.241
smtp.mydomain.net. 856 IN A 172.16.1.242

We have an override for the record that is behaving this way.

172.17.23.231	smtp.mydomain.net. smtp

I am seeing a bunch of these in the logs. Could they be related?

pdns_recursor[6020]: STL error: Tried to remove unlisted fd 95 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 94 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 72 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 102 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 101 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 110 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 96 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 107 from
multiplexer
pdns_recursor[6020]: STL error: Tried to remove unlisted fd 105 from
multiplexer

# rpm -qif /usr/sbin/pdns_recursor
Name        : pdns-recursor                Relocations: (not
relocatable)
Version     : 3.1.7                             Vendor: PowerDNS.COM BV
Release     : 1                             Build Date: Tue 24 Jun 2008
06:32:27 PM UTC
Install Date: Tue 23 Jun 2009 10:45:44 PM UTC      Build Host:
adsl-xs4all.ds9a.nl
Group       : System/DNS                    Source RPM:
pdns-recursor-3.1.7-1.src.rpm
Size        : 2336542                          License: GPL
Signature   : (none)
Summary     : extremely powerful and versatile recursing nameserver
Description :
PowerDNS is a versatile nameserver which supports a large number
of different backends ranging from simple zonefiles to relational
databases and load balancing/failover algorithms.

This RPM is semi-statically compiled and should work on all Linux
distributions.

# uname -a
Linux localhost 2.6.18-53.1.21.el5 #1 SMP Tue May 20 09:35:07 EDT 2008
x86_64 x86_64 x86_64 GNU/Linux

# cat /etc/*release
CentOS release 5 (Final)

# md5sum /usr/sbin/pdns_recursor
295dd8792670490c205ddc88694f7c8a  /usr/sbin/pdns_recursor

# ls -l /usr/sbin/pdns_recursor
-rwxr-xr-x 1 root root 1741560 Jun 24  2008 /usr/sbin/pdns_recursor

# cat recursor.conf 
aaaa-additional-processing=off
allow-from=127.0.0.0/8, 10.100.0.0/16
dont-query=127.0.0.0/8, 192.168.0.0/16, 172.16.0.0/12, ::1/128,
fe80::/10
config-dir=/etc/powerdns/
forward-zones-file=/etc/powerdns/zones.conf
daemon=yes
export-etc-hosts=on
fork=yes
local-port=53
log-common-errors=no
max-cache-entries=1000000
max-tcp-clients=5000
server-id=PowerDNS
local-address=127.0.0.1,10.199.78.231,10.199.79.231

# cat zones.conf
a.b.mydomain.local=172.17.18.241;172.17.18.242
a.c.mydomain.local=172.17.18.241;172.17.18.242
a.d.mydomain.local=172.17.18.241;172.17.18.242
a.e.mydomain.local=172.17.18.241;172.17.18.242
35.172.in-addr.arpa=172.17.18.241;172.17.18.242
50.172.in-addr.arpa=172.17.18.241;172.17.18.242
70.172.in-addr.arpa=172.17.18.241;172.17.18.242
80.172.in-addr.arpa=172.17.18.241;172.17.18.242
100.172.in-addr.arpa=172.17.18.241;172.17.18.242
110.172.in-addr.arpa=172.17.18.241;172.17.18.242
a.mydomain.local=172.17.18.241;172.17.18.242
mydomain.net=172.17.18.241;172.17.18.242

I also dumped stats before I restarted pdns_recursor to clear the
problem.

# more pdns_stats.6020 pdns_stats.6021
::::::::::::::
pdns_stats.6020
::::::::::::::
all-outqueries: 655490
answers0-1: 92199
answers100-1000: 225015
answers10-100: 81537
answers1-10: 105986
answers-slow: 20485
cache-entries: 426087
cache-hits: 79792
cache-misses: 445430
chain-resends: 5850
client-parse-errors: 0
concurrent-queries: 2
dlg-only-drops: 0
negcache-entries: 15747
noerror-answers: 327209
nsspeeds-entries: 5142
nsset-invalidations: 4781
nxdomain-answers: 134977
outgoing-timeouts: 27089
qa-latency: 101372
questions: 525311
resource-limits: 0
server-parse-errors: 2
servfail-answers: 63119
spoof-prevents: 0
sys-msec: 64797
tcp-client-overflow: 0
tcp-outqueries: 442
tcp-questions: 665
throttled-out: 61556
throttle-entries: 691
unauthorized-tcp: 0
unauthorized-udp: 0
unexpected-packets: 8
uptime: 21003
user-msec: 124633

::::::::::::::
pdns_stats.6021
::::::::::::::
all-outqueries: 7140205
answers0-1: 6997444
answers100-1000: 1985236
answers10-100: 1072119
answers1-10: 2350760
answers-slow: 143908
cache-entries: 992443
cache-hits: 6723813
cache-misses: 5825654
chain-resends: 96565
client-parse-errors: 0
concurrent-queries: 33
dlg-only-drops: 0
negcache-entries: 165190
noerror-answers: 7995482
nsspeeds-entries: 21540
nsset-invalidations: 129669
nxdomain-answers: 3379716
outgoing-timeouts: 186738
qa-latency: 40249
questions: 12549587
resource-limits: 0
server-parse-errors: 18
servfail-answers: 1174280
spoof-prevents: 0
sys-msec: 345213
tcp-client-overflow: 0
tcp-outqueries: 1688
tcp-questions: 3119
throttled-out: 1903336
throttle-entries: 3861
unauthorized-tcp: 0
unauthorized-udp: 0
unexpected-packets: 37
uptime: 21009
user-msec: 1680884