Hello fellow Knot users, We're using Knot on some of our public authoritative servers. We operate a hidden primary configuration where there are two internal primary servers sending notifies to publicly accessible servers whenever zones change (ofc internal servers allow zone transfers & queries from the knot servers). By design, our hidden internal primary servers operate in a hot/cold setup - one of them is answering to zone transfers / sending out notifies and the other one is not (dns server software is not running on the cold server). This configuration causes knot to log alarming errors: Feb 1 17:28:45 ns2 knotd[624]: info: [zone.fi.] refresh, remote 10.54.54.1@8054, remote serial 2021083015, zone is up-to-date, expires in 864000 seconds Feb 1 17:28:45 ns2 knotd[624]: info: [zone.fi.] refresh, remote hidden-ns-2.internal, address 10.54.54.2@8054, failed (connection reset) Feb 1 17:28:45 ns2 knotd[624]: info: [zone.fi.] refresh, remote hidden-ns-2.internal, address [ipv6_address]@8054, failed (connection reset) Feb 1 17:28:45 ns2 knotd[624]: warning: [zone.fi.] refresh, remote hidden-ns-2.internal not usable Feb 1 17:28:45 ns2 knotd[624]: error: [zone.fi.] refresh, failed (no usable master), next retry at 2024-02-01T17:58:45+0200 Feb 1 17:28:45 ns2 knotd[624]: error: [zone.fi.] zone event 'refresh' failed (no usable master) Specifically, error "(no usable master)" is worrying - knot is able to reach hidden-ns-1.internal and verify that the zone it has is up-to-date. Also zone updates work normally and the zones don't seem to expire away (as zones should do if no master is reachable for an extended period of time). Looks like this error appeared in version 3.3.0. 3.2.9 did not log similar errors (except in cases where all primaries really were unreachable). Has there been some design change in 3.3.0 (ie is this intentional) or could this be a bug? Or could it be related to our configuration? Our configuration relies heavily on templates. These should be the important bits from knot's config, with ipv6 addresses hidden: acl: - id: "hidden-ns-1.internal" address: [ 10.54.54.1, ipv6_address ] action: notify - id: "hidden-ns-2.internal" address: [ 10.54.54.2, ipv6_address ] action: notify remote: - id: "hidden-ns-1.internal" address: [ 10.54.54.1@8054, ipv6_address@8054 ] via: [ x.x.x.x, ipv6_address ] - id: "hidden-ns-2.internal" address: [ 10.54.54.2@8054, ipv6_address@8054 ] via: [ x.x.x.x, ipv6_address ] template: - id: default storage: /var/lib/knot/zones master: hidden-ns-1.internal master: hidden-ns-2.internal acl: hidden-ns-1.internal acl: hidden-ns-2.internal semantic-checks: false global-module: mod-rrl/default zone: - domain: zone.fi -- Juha Suhonen Senior Systems Specialist CSC - Tieteen tietotekniikan keskus Oy juha.suhonen(a)csc.fi