If you use webmin go to "Zone Defaults" and enter "none" into the "Allow transfers from..." text box.
If you don't use webmin go to the file "/etc/bind/named.conf.options" and enter the following:
[sourcecode language="plain"]
allow-transfer {
"none";
};
[/sourcecode]
If this file doesn't exist for you, just chech the config file "/etc/bin/named.conf" if there is an include with the ending ".conf.options" use that and otherwise enter directly in named.conf as last possibility (but check other included config files if it exists elsewhere).