[Pdns-users] Bad cache TTL with pdns-resursor

[Michael FROMENT]

Hi bert,

Thanks for the answer I've uderstand the strange ttl response when the 
answer come from the paquet cache.
Now here is a little more strange problem
########################################
;; QUESTION SECTION:
;s4.noelshack.com.              IN      A
;; ANSWER SECTION:
s4.noelshack.com.       3600    IN      CNAME   noelshack.com.
noelshack.com.          3600    IN      A       91.121.63.175
########################################
;; QUESTION SECTION:
;s4.noelshack.com.              IN      NS
;; ANSWER SECTION:
s4.noelshack.com.       2175    IN      CNAME   noelshack.com.
noelshack.com.          85974   IN      NS      ns1.afraid.org.
noelshack.com.          85974   IN      NS      ns4.afraid.org.
noelshack.com.          85974   IN      NS      ns2.afraid.org.
noelshack.com.          85974   IN      NS      ns3.afraid.org.
########################################
;; QUESTION SECTION:
;noelshack.com.                 IN      SOA
;; ANSWER SECTION:
noelshack.com.          3535    IN      SOA     ns1.afraid.org. 
dnsadmin.afraid.org. 1110170003 86400 7200 2419200 3600
########################################



The zone noelshack.com. have moved since more than a week at 
ns-01.odysseeinteractive.com
The correct answer from another pdns_recursor :
#########################################
;; QUESTION SECTION:
;noelshack.com.                 IN      SOA
;; ANSWER SECTION:
noelshack.com.          86281   IN      SOA     
ns-01.odysseeinteractive.com. noc.odysseeinteractive.com. 2011122801 
86400 7200 604800 86400
#########################################

The ttl on this zone nerver goes to 0 and moreover after 1 hour ( the 
paquet cache duration) is sometime increased.
We have around 100 servers and half are affected by this problem... The 
only solution I've find is to wipe the cache for this dns entrie.
There is no reason to do this since 1 week as the TTL on the soa is only 
86400...

Any ideas?

Kind regards

Michael

On 12/29/2011 04:20 PM, bert hubert wrote:
> Hi Michael,
>
> The SOA will indeed probably not go to zero because it will have been
> renewed in that time. PowerDNS Recursor 3.3 and later take care to decrement
> the TTL when serving contents from the packet cache.
>
> So when you don't see it going down in 3.2, that is correct, and maybe a bit
> strange, but not a bug.
>
> 	Bert
>
>
> On Thu, Dec 29, 2011 at 10:08:53AM +0100, Michael FROMENT wrote:
>> Hi,
>>
>> I have some strange cached TTL on my pdns-recursor ( version 3.2-4 under
>> debian ).
>> When I query my recursor the TTL doesn't decrease by 1 second. Moreover the
>> TTL never goes to 0 so the zone never expire in cache.
>> As an example:
>>
>> root at BBK2NS:~# dig soa google.com @89.2.0.1
>> ;; ANSWER SECTION:
>> google.com.             569     IN      SOA     ns1.google.com.
>> dns-admin.google.com. 1472387 7200 1800 1209600 300
>>
>> ;; Query time: 0 msec
>> ;; SERVER: 89.2.0.1#53(89.2.0.1)
>> ;; WHEN: Thu Dec 29 10:02:46 2011
>> ;; MSG SIZE  rcvd: 78
>>
>> root at BBK2NS:~# dig soa google.com @89.2.0.1
>> ;; ANSWER SECTION:
>> google.com.             40      IN      SOA     ns1.google.com.
>> dns-admin.google.com. 1472388 7200 1800 1209600 300
>>
>> ;; Query time: 0 msec
>> ;; SERVER: 89.2.0.1#53(89.2.0.1)
>> ;; WHEN: Thu Dec 29 10:02:47 2011
>> ;; MSG SIZE  rcvd: 78
>>
>> root at BBK2NS:~# dig soa google.com @89.2.0.1
>> ;; ANSWER SECTION:
>> google.com.             562     IN      SOA     ns1.google.com.
>> dns-admin.google.com. 1472388 7200 1800 1209600 300
>>
>> ;; Query time: 0 msec
>> ;; SERVER: 89.2.0.1#53(89.2.0.1)
>> ;; WHEN: Thu Dec 29 10:04:08 2011
>> ;; MSG SIZE  rcvd: 78
>>
>> Is this a known bug on the recursor?
>>
>> Kind Regards
>>
>> Michael
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