acl "trusted" {
        #x.x.x.x;
};
options {
        directory "/var/cache/bind";

        recursion yes;                # enables recursive queries
        allow-recursion { any; };     # allows recursive queries from "trusted” clients i.e. LB only
        listen-on { dns_ip_addr; };   # ns1 IP address - listen on this address only
        allow-transfer { none; };      # disable zone transfers by default

        forwarders {
                dns_forwarder;
                external_dns;
                8.8.4.4;
        };

        // If there is a firewall between you and nameservers you want
        // to talk to, you may need to fix the firewall to allow multiple
        // ports to talk.  See http://www.kb.cert.org/vuls/id/800113

        // If your ISP provided one or more IP addresses for stable
        // nameservers, you probably want to use them as forwarders.
        // Uncomment the following block, and insert the addresses replacing
        // the all-0's placeholder.

        // forwarders {
        //      0.0.0.0;
        // };

        //========================================================================
        // If BIND logs error messages about the root key being expired,
        // you will need to update your keys.  See https://www.isc.org/bind-keys
        //========================================================================
        dnssec-validation no;

        auth-nxdomain no;    # conform to RFC1035
        listen-on-v6 { any; };
};