[Pdns-users] How should my backend tell pdns that pdns_server that it has changed the zone

jb-wisemo jb-powerdns at wisemo.com
Tue Sep 24 15:00:48 UTC 2019

On 24/09/2019 14:25, Pieter Lexis wrote:
> Hi Jakob,
> On 9/24/19 12:31 AM, jb-wisemo via Pdns-users wrote:
>> I am creating a custom master-mode backend for a special use. But some
>> questions are left open or vague by the documentation, here is the first
>> one:
>> How shall I tell pdns_server that I have changed my zone and increased
>> the zone serial in the database?
>> Idea is to trigger notify and replication to ordinary slaves as quickly
>> as possible, being able to tell code elsewhere that the changes should
>> now be available in the global DNS (doing my own TTL calculations).
> Increasing the SOA serial will be enough. PowerDNS will check the
> serials every slave-cycle-interval[1] seconds and queue NOTIFY messages
> to slaves when needed.
> If that is not fast enough for you, you could have your provisioning
> system send the NOTIFY by itself to the slaves.
> Best regards,
> Pieter
> 1 -
> https://docs.powerdns.com/authoritative/settings.html#setting-slave-cycle-interval

Indeed, having pdns_server poll the database at a regular interval is too
slow for my use case.  Sending an external NOTIFY to slaves and having them
attempt an AXFR makes me worry if PowerDNS will be ready to answer with the
latest database contents, as opposed to returning something cached or
partially processed (DNSSEC rectification etc.).

This is why I am looking for a way to make PowerDNS check the serial in the
database and trigger all resulting actions in the correct order as soon as
the database management process has written a new set of changes. Almost as
if the "cycle interval" had ended at exactly that moment, for that 

I was hoping for something available via pdnsutil, a call that could be 
from the backend, or less securely (increases attack surface) the REST API.

Ideally, the idle CPU/memory load would be kept low between changes.


Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
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WiseMo - Remote Service Management for PCs, Phones and Embedded

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