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

jb-wisemo jb-powerdns at wisemo.com
Thu Sep 26 22:51:27 UTC 2019

They're multiple technical reasons for not running PowerDNS on most of 
the slave

Besides, each server typically runs only one DNS authoritative server 
just not the same.  And the list of zones to slave is short enough to be 
loaded from a
script-generated config.

There's also the security aspect of not sharing the ZSK key with the 
slaves, feeding
them only a presigned zone or zone delta (once IXFR is actually 

PowerDNS documentation for slaving presigned zones indicate a somewhat
incomplete implementation (ignores master's choice of NSEC3 records), making
other DNS implementations preferable for slaves.

On 26/09/2019 08:13, Thomas Mieslinger wrote:
> Depending on the setting of records ttl, max-cache size, packet-cache
> size pdns will do a select of the name in the underlying database.
> Setting caching and ttl to reasonable low values will force pdns to do
> selects in the database.
> To me it is a lot easier to monitor the mysql "seconds behind master"
> metric to be sure that all pdns have the latest data instead of having
> to monitor the zone serial of many zones on many servers.
> Is there a technical or organizational reason to run different DNS
> Server Softwares in your setup? Usually you need more FTE if you are
> running bind, knot, nsd, powerdns in parallel instead of using only one
> software.
> On 9/25/19 10:28 PM, jb-wisemo via Pdns-users wrote:
>> Most of the slaves are not running powerdns.  So can't use database
>> replication to the slaves.
>> And even if they did run powerdns, they would still need a way to
>> tell pdns_server that the database hasbeen updated by replication.
>> On 24/09/2019 19:28, Satya Sharma wrote:
>>> Use SQL replication on all the Slave servers. Making SQL replication
>>> will add speed.
>>> On Tue, 24 Sep 2019 00:31:30 +0200 <jb-powerdns at wisemo.com
>>> <mailto:jb-powerdns at wisemo.com>> wrote:
>>>     Date: Tue, 24 Sep 2019 00:31:30 +0200
>>>     From: jb-wisemo <jb-powerdns at wisemo.com
>>>     <mailto:jb-powerdns at wisemo.com>>
>>>     To: pdns-users at mailman.powerdns.com
>>>     <mailto:pdns-users at mailman.powerdns.com>
>>>     Subject: [Pdns-users] How should my backend tell pdns that
>>> pdns_server
>>>             that it has changed the zone
>>>     Message-ID: <cabf1a44-17f8-95e6-ef86-881c0520f2a2 at wisemo.com
>>> <mailto:cabf1a44-17f8-95e6-ef86-881c0520f2a2 at wisemo.com>>
>>>     Content-Type: text/plain; charset=utf-8; format=flowed
>>>     Hi,
>>>     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).
>>>     Zone may be unsigned or NSEC3-wide, as NSEC3-narrow doesn't seem to
>>>     support replication to slaves that don't have the ZSK private key.


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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