[knot-dns-users] knsupdate refused after some time

Hi, I'm using a script to dynamically update an IPv4. After some time, the update gets refused. Script: KNOT_SERVER='194.59.205.151' KNOT_KEY='hmac-sha256:dyndns:somerandomkey' croot='schafweide.org' domain='home.schafweide.org' knsupdate -y "${KNOT_KEY}" <<EOF server ${KNOT_SERVER} zone ${croot}. update delete $domain 60 A update add $domain 60 A $1 send quit EOF Error message: ;; ->>HEADER<<- opcode: UPDATE; status: REFUSED; id: 61622 ;; Flags: qr; ZONE: 1; PREREQ: 0; UPDATE: 0; ADDITIONAL: 1 ;;schafweide.org. IN SOA dyndns. 0 ANY TSIG hmac-sha256. 1556969992 300 32 21LTowPMGditU419LSHez6CRtRblLLZZcxtu89RCocI= 61622 NOERROR 0 ;; ERROR: update failed with error 'REFUSED' After "systemctl restart knot" the update just runs fine. I'm wondering what's wrong there. Regards Bjoern