options {
  directory "/var/cache/bind";
  dnssec-validation auto;

  listen-on-v6 { any; };
  allow-query { any; };

  max-cache-size 30%;
  querylog yes;

% if type == 'master':
  notify yes;
  also-notify { ${' '.join(sorted(f'{ip};' for ip in slave_ips))} };
  allow-transfer { ${' '.join(sorted(f'{ip};' for ip in slave_ips))} };
% endif
};