After several successful attempts using the exact same configuration and steps mentioned in early question here <https://lists.nic.cz/pipermail/knot-dns-users/2020-January/001744.html> or here <https://gist.github.com/azzamsa/24dca2e201c3bea4f489a09f7a3a8716> (with better preview) I get stuck with no usable master The master side Jan 12 07:35:12 knot-master-1.novalocal knotd[12007]: info: [namadomain14.com.] zone file updated, serial 2018070410 Jan 12 07:35:12 knot-master-1.novalocal knotd[12007]: warning: [namadomain14.com.] notify, outgoing, remote slaveip@53, s...TAUTH' Jan 12 07:37:18 knot-master-1.novalocal knotd[12007]: info: [namadomain14.com.] control, received command 'zone-begin' Jan 12 07:37:32 knot-master-1.novalocal knotd[12007]: info: [namadomain14.com.] control, received command 'zone-set' Jan 12 07:37:37 knot-master-1.novalocal knotd[12007]: info: [namadomain14.com.] control, received command 'zone-commit' Jan 12 07:37:37 knot-master-1.novalocal knotd[12007]: info: [namadomain14.com.] zone file updated, serial 2018070410 -> 2018070412 Jan 12 07:37:37 knot-master-1.novalocal knotd[12007]: warning: [namadomain14.com.] notify, outgoing, remote slaveip@53, s...TAUTH' Jan 12 07:37:41 knot-master-1.novalocal knotd[12007]: info: control, received command 'zone-read' Jan 12 07:38:11 knot-master-1.novalocal knotd[12007]: info: [namadomain14.com.] control, received command 'zone-notify' Jan 12 07:38:11 knot-master-1.novalocal knotd[12007]: warning: [namadomain14.com.] notify, outgoing, remote slaveip@53, s...TAUTH' The slave side Jan 12 07:34:54 knot-slave-1 knotd: info: control, received command 'conf-read' Jan 12 07:35:19 knot-slave-1 systemd-logind: Removed session 2. Jan 12 07:35:20 knot-slave-1 knotd: info: control, received command 'conf-begin' Jan 12 07:35:20 knot-slave-1 knotd: notice: control, persistent configuration database not available Jan 12 07:35:20 knot-slave-1 knotd: info: control, received command 'conf-set' Jan 12 07:35:20 knot-slave-1 knotd: info: control, received command 'conf-set' Jan 12 07:35:20 knot-slave-1 knotd: info: control, received command 'conf-set' Jan 12 07:35:20 knot-slave-1 knotd: info: control, received command 'conf-commit' Jan 12 07:35:20 knot-slave-1 knotd: info: [namadomain14.com.] zone will be loaded Jan 12 07:35:20 knot-slave-1 knotd: info: [namadomain14.com.] failed to parse zone file (not exists) Jan 12 07:35:21 knot-slave-1 knotd: warning: [namadomain14.com.] refresh, remote master1 not usable Jan 12 07:35:21 knot-slave-1 knotd: error: [namadomain14.com.] refresh, failed (no usable master) Jan 12 07:35:23 knot-slave-1 knotd: warning: [namadomain14.com.] refresh, remote master1 not usable Jan 12 07:35:23 knot-slave-1 knotd: error: [namadomain14.com.] refresh, failed (no usable master) Jan 12 07:35:27 knot-slave-1 knotd: info: control, received command 'zone-read' Jan 12 07:35:29 knot-slave-1 knotd: info: control, received command 'zone-read' Jan 12 07:35:34 knot-slave-1 knotd: warning: [namadomain14.com.] refresh, remote master1 not usable Jan 12 07:35:34 knot-slave-1 knotd: error: [namadomain14.com.] refresh, failed (no usable master) Jan 12 07:36:31 knot-slave-1 knotd: warning: [namadomain14.com.] refresh, remote master1 not usable Jan 12 07:36:31 knot-slave-1 knotd: error: [namadomain14.com.] refresh, failed (no usable master) Jan 12 07:37:14 knot-slave-1 knotd: info: [namadomain14.com.] control, received command 'zone-begin' Jan 12 07:37:55 knot-slave-1 knotd: info: [namadomain14.com.] control, received command 'zone-abort' Jan 12 07:38:19 knot-slave-1 knotd: info: control, received command 'zone-read' Jan 12 07:39:12 knot-slave-1 knotd: warning: [namadomain14.com.] refresh, remote master1 not usable Jan 12 07:39:12 knot-slave-1 knotd: error: [namadomain14.com.] refresh, failed (no usable master) Problems Previously, even though I have ‘NO AUTH’ in master side. The zone in slave still crated, because I don’t get no usable master. But the sudden there is no usable master. I’ve tried: - sudo service knot restart - remove everything -> reinstall everything Both give me no luck. Thank you in advance.