Today I had to do some bind9 configuration and here are the results for my future self.
Nowadays the Debian bind package is prepared to use IPv6. In case your server has no IPv6 connectivity yet, lots of errors appear in the logs. Most of them can be ignored, but at least they look ugly. So if you know that you do not need IPv6 add ‘-4’ to the OPTIONS-line in /etc/default/bind9.
If you get an error like “refused notify from non-master” and the IP of non-master is your own host, you need to accept notifies from yourself. Just add something like ‘allow-notfy { n.m.o.p; };’ to the options{}-section (n.m.o.p should be your own IP). On Debian systems this is in /etc/bind/named.conf.options.