[Kea-users] ddns fails with powerDNS (Failed PreRequisites check)

Thomas Markwalder tmark at isc.org
Wed Feb 6 11:47:27 UTC 2019


We migrated to gitlab, the old Trac ticket can be found here:


We did correct that particular issue in Kea 1.2.  If you are using an
earlier version,  please upgrade.
If you are already using 1.2 or later you may have uncovered something
new, in which case I would
encourage you to open a issue in gitlab:


You'll need to register (if you haven't already) and then select the Kea
We would need PCAPs of the DDNS messages plus whatever logs from
PowerDNS to start with.


Thomas Markwalder
ISC Software Engineering

On 2/6/19 3:44 AM, MRob wrote:
>> Has anyone found how to make kea-ddns work with PowerDNS? pdns logs
>> suggest:
>> pdns[20989]: UPDATE (50855) from for lan.: Failed
>> PreRequisites check, returning 6
>> The query log shows only some normal SELECT statements. If it's not a
>> known problem can anyone show how to find what the DNS UPDATE command is
>> being sent to the DNS server to diagnose?
>> Someone else had problem but couldn't get resolution:
>> https://github.com/PowerDNS/pdns/issues/5830
> Problem seems to be using TSIG signed DNSUPDATE requests. There used
> to be a Kea bug
> http://kea.isc.org/ticket/5071#ticket
> But the link is dead. Is that bug fixed? Is the problem with Kea or
> maybe the older version of powerDNS?
> Question - after I removed TSIG the initial forward and reverse
> DNSUPDATE commands succeed:
> DHCP_DDNS_ADD_SUCCEEDED DHCP_DDNS Request ID xxx: successfully added
> the DNS mapping addition for this request: Type: 0 (CHG_ADD)
> But Kea does another CHG_ADD only a minute later and it fails:
> port:5353, rejected a DNS update request to replace the
> address mapping for FQDN, wkst4.lan., with an RCODE: 8
> DHCP_DDNS_ADD_FAILED DHCP_DDNS Request ID yyy: Transaction outcome
> Status: Failed, Event: UPDATE_FAILED_EVT,  Forward change: failed, 
> Reverse change: failed,  request: Type: 0 (CHG_ADD)
> Is this a problem or can it be ignored? Is it due to setting
> "override-no-update": true and "override-client-update": true?
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