I'm running a six server cluster including 3 dns servers. After many years of running on VMware I've started to make the move to openstack. The least risky start was to convert my 2nd dns slave which was successful in that I have a working server that appears not to be giving any errors. I opened the firewall to dns and ssh and I can query the server externally. I made a change to a DNS record (namely the one that points to itself because it's external IP necessarily had to change) to test it updates, and it doesn't. I changed all the hosts files to also point to it, still no joy. I queried the database and dns_rr table is not being updated, and of course the bind zone file is consistent with the database. (wrong) It's counterpart slave dns server I haven't moved still works perfectly. Before I go converting anymore VMs in the cluster is there a diagnostic technique someone can point me to to check why it isn't updating? I'm running debian buster and currently on Ispconfig 3.2.2.