[Pdns-users] PDNS inconsistent behavior for SOA record

[David]

On 2018-06-05 9:57 AM, Anthony fajri wrote:
> Hi Expert,
> we are using PDNS for our 3GPP DNS Server.
> we are using PDNS 2.9.22.6 on Centos 5.
> 
> we want to achieve following objective:
> - to return TTL of SOA record as 60s for specific IP
> - to return TTL of SOA record as 7 days for all IP
> 
> our configuration is as following:
> if(($qtype eq "SOA" || $qtype eq "ANY") && ($qname =~ 
> /epc.mnc001.mcc001.3gppnetwork.org/ 
> <http://epc.mnc001.mcc001.3gppnetwork.org/>)) {
>          if($ip eq "200.200.100.1" || $ip eq "200.200.100.5" || $ip eq 
> "200.200.100.6" || $ip eq "200.200.99.1" || $ip eq "200.200.99.4" || $ip 
> eq "200.200.99.7" || $ip eq "10.4.7.200") {
>                  if($qtype eq "SOA") {
> #                       print 
> "DATA\t$qname\t$qclass\tSOA\t20\t1\tgrxdns1.epc.mnc001.mcc001.3gppnetwork.org 
> <http://tgrxdns1.epc.mnc001.mcc001.3gppnetwork.org>. 
> postmaster.epc.mnc001.mcc001.3gppnetwork.org 
> <http://postmaster.epc.mnc001.mcc001.3gppnetwork.org>. 2013050400 3600 
> 3600 604800 600\n";
>                          print 
> "DATA\t$qname\t$qclass\tSOA\t60\t1\tgrxdns1.epc.mnc001.mcc001.3gppnetwork.org 
> <http://tgrxdns1.epc.mnc001.mcc001.3gppnetwork.org>. 
> postmaster.epc.mnc001.mcc001.3gppnetwork.org 
> <http://postmaster.epc.mnc001.mcc001.3gppnetwork.org>. 2018060100 900 
> 900 1800 60\n";
>                  }
>          } else {
>                  print 
> "DATA\t$qname\t$qclass\tSOA\t604800\t1\tgrxdns1.epc.mnc001.mcc001.3gppnetwork.org 
> <http://tgrxdns1.epc.mnc001.mcc001.3gppnetwork.org>. 
> postmaster.epc.mnc001.mcc001.3gppnetwork.org 
> <http://postmaster.epc.mnc001.mcc001.3gppnetwork.org>. 2013050400 3600 
> 3600 604800 600\n";
>    }
> }
> 
> 
> however, the result is inconsistent.
> sometime it returns the exepcted value (TTL of 60 second), but some 
> other time it returns with default value.

I'm guessing that super old version still has a packet cache on it, so 
that's where it's going to cache your response regardless of source IP 
address for a period of time. It may or may not be possible to disable 
that on that version.