[Kea-users] DDNS RRset exists prerequisite not satisfied (NXRRSET)

[listy]

whoahh - as a note to myself, perhaps others.

If my Kea also logs something like:
...
Oct 27 08:37:31 kea-dhcp4[2507637]: ERROR 
ALLOC_ENGINE_V4_ALLOC_ERROR [hwtype=1 fc:91:5d:dc:fc:da], 
cid=[01:fc:91:5d:dc:fc:da], tid=0x20725920: error during 
attempt to allocate an IPv4 address: unable to execute for 
<UPDATE lease4 SET address = ?, hwaddr = ?, client_id = ?, 
valid_lifetime = ?, expire = ?, subnet_id = ?, fqdn_fwd = ?, 
fqdn_rev = ?, hostname = ?, state = ?, user_context = ?, 
relay_id = ?, remote_id = ?, pool_id = ? WHERE address = ? 
AND expire = ?>, reason: Lock wait timeout exceeded; try 
restarting transaction (error code 1205)
...

then check your SQL logs right away, eg.:
...
2026-10-27  8:40:30 36817 [Warning] Aborted connection 36817 
to db: 'kea_mine_lease' user: 'kea_server' host: 'localhost' 
(Got an error reading communication packets)
2026-10-27  8:40:30 36815 [Warning] Aborted connection 36815 
to db: 'kea_mine_lease' user: 'kea_server' host: 'localhost' 
(Got an error reading communication packets)
2026-10-27  8:40:51 36865 [Warning] Aborted connection 36865 
to db: 'kea_mine_lease' user: 'kea_server' host: 'localhost' 
(Got an error reading communication packets)
...

all this was caused by "some" issue with my MariaDB.

btw. perhaps outside of the scope of this list, worth asking 
as db experts might be here:
Are there any good/best practices for Kea<=>SQL server 
tweaking/tuning?
For me this happened at night, likely when a backup was 
taking place.

many thanks, L.