When I run collectd on my desktop PC, the DNS plugin doesn't collect response statistics. Values for responses in dns_octets.rrd are all zero, and no rcode rrd-s are created.
Collectd 5.0.3 built from source. But the same stands for Collectd 4.10.1 built for Squeeze.
I tried to understand how collectd works. So I used Wireshark to create a dump file of some DNS queries.
Then I processed the capture file by hand to see the expected result.
Lastly I dumped the rrd database with the command rrdtool dump dns_octets.rrd > dns_octets.xml
Here you can see the two relevant rows:
<!-- 2012-03-14 11:48:20 CET / 1331722100 --> <row><v>4.9280000000e+01</v><v>0.0000000000e+00</v></row>
<!-- 2012-03-14 11:48:30 CET / 1331722110 --> <row><v>1.2320000000e+01</v><v>0.0000000000e+00</v></row>
As the first value refers to queries, the second to responses, I added up the two numbers in for query bytes. I got 61.6 bytes/10 sec, what seems to be correct. But in the second column there are only zero values, although I saw 968 bytes of responses in the capture file.
I have no clue what could cause this.