nano /etc/bind/ipa-options-ext.conf

 * User customization for BIND named
 *
 * This file is included in /etc/bind/named.conf and is not modified during IPA
 * upgrades.
 *
 * It must only contain "options" settings. Any other setting must be
 * configured in /etc/bind/ipa-ext.conf.
 *
 * Examples:
 * allow-recursion { trusted_network; };
 * allow-query-cache { trusted_network; };
 */

/* turns on IPv6 for port 53, IPv4 is on by default for all ifaces */
listen-on-v6 { any; };

/* dnssec-enable is obsolete and 'yes' by default */
dnssec-validation no;