You probably heard of the three steps on how to debug networking issues…

  1. It’s not DNS
  2. There’s no way it’s DNS
  3. It was DNS

While this is not only funny, but also true, you can do your part to prevent such issues.

When you change the configuration for BIND, you should make sure it is still working.

check bind configuration

$ named-checkconf /path/to/named.conf

The path depends on your distribution. For Ubuntu 20.04 it is /etc/bind/named.conf.

check bind zone file

$ named-checkzone example.net /etc/bind/example.net

The path and the name of the configuration database was chosen by you or your administrator.