[knot-dns-users] knotc zone-retransfer not always working as expected

zone-refresh [<zone>...] Force slave zone refresh. zone-retransfer [<zone>...] Force slave zone retransfer (no serial check). I would expect that retransfer does a complete AXFR. But instead it just does sometimes a refresh: info: [at.] control, received command 'zone-retransfer' info: [at.] refresh, outgoing, 83.1.2.3@53: remote serial 2018011647, zone is up-to-date info: [at.] control, received command 'zone-retransfer' info: [at.] refresh, outgoing, 83.1.2.3@53: remote serial 2018011647, zone is up-to-date info: [at.] control, received command 'zone-refresh' info: [at.] refresh, outgoing, 2a02:111:9::5@53: remote serial 2018011647, zone is up-to-date info: [at.] control, received command 'zone-refresh' info: [at.] refresh, outgoing, 2a02:111:9::5@53: remote serial 2018011647, zone is up-to-date info: [at.] control, received command 'zone-refresh' info: [at.] refresh, outgoing, 2a02:111:9::5@53: remote serial 2018011647, zone is up-to-date info: [at.] control, received command 'zone-retransfer' info: [at.] AXFR, incoming, 2a02:111:9::5@53: starting Seen with 2.6.3-1+ubuntu14.04.1+deb.sury.org+1 regards Klaus