[Pdns-users] Have I got a good one....

bert hubert bert.hubert at netherlabs.nl
Sat Mar 4 11:40:04 UTC 2006


> Based on my experience with pdns, I'd suspect the pdns doesn't
> like the bad values, while bind closes its eyes hard and skates.

This is generally not the case, we try to keep things working, PowerDNS is a
"working man's nameserver", it is not pedantic, or at least, not by design.

Getting back to 'messageboardoflove.com', it has some problems.

Its nameservers are called 'ns1.infopop.cc' and 'ns2.infopop.cc'. Each of
these nameserver is listed with two IP addresses in the .cc nameserver:

;; ADDITIONAL SECTION:
NS1.infopop.cc.         172800  IN      A       63.251.4.129
NS1.infopop.cc.         172800  IN      A       63.251.6.129
NS2.infopop.cc.         172800  IN      A       63.251.4.130
NS2.infopop.cc.         172800  IN      A       63.251.6.130

However, 2 of these four IP addresses don't work (63.251.6.129 and
63.251.6.130), and PowerDNS does not try all of them.

I've fixed that now:
Mar 04 12:35:03 [2] www.messageboardoflove.com: Trying to resolve NS ns1.infopop.cc (1/2)
Mar 04 12:35:03 [2]   ns1.infopop.cc: Looking for CNAME cache hit of 'ns1.infopop.cc|CNAME'
Mar 04 12:35:03 [2]   ns1.infopop.cc: No CNAME cache hit of 'ns1.infopop.cc|CNAME' found
Mar 04 12:35:03 [2]   ns1.infopop.cc: Looking for direct cache hit of 'ns1.infopop.cc|A', negative cached: 0
Mar 04 12:35:03 [2]   ns1.infopop.cc: Found cache hit for A: 63.251.4.129[ttl=291] 63.251.6.129[ttl=172791]
Mar 04 12:35:03 [2] www.messageboardoflove.com: Resolved 'messageboardoflove.com' NS ns1.infopop.cc to 63.251.6.129, asking 'www.messageboardoflove.com|A'
Mar 04 12:35:05 [2] www.messageboardoflove.com: timeout resolving
Mar 04 12:35:05 [2] www.messageboardoflove.com: Resolved 'messageboardoflove.com' NS ns1.infopop.cc to 63.251.4.129, asking 'www.messageboardoflove.com|A'
Mar 04 12:35:05 [2] www.messageboardoflove.com: Got 5 answers from ns1.infopop.cc (63.251.4.129), rcode=0, in 160ms

It also shuffles a bit so it asks all of the nameservers over time,
spreading the load, while caching non-behaving IP addresses.

> At the very least it's a nice place if you want somewhere
> authoritative to point to saying it's not your fault :-)

In some real sense it is not his fault, messageboardoflove.com is
misconfigured, but PowerDNS could really try harder, and it does so now.

A fixed build will appear on http://svn.powerdns.com/snapshots/565/ in a few
minutes.

Regards,

Bert

-- 
http://www.PowerDNS.com      Open source, database driven DNS Software 
http://netherlabs.nl              Open and Closed source services


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