options {
        directory "/var/named";
}

(...)

zone "dominio.com.br" in { 
 type master; 
 notify no; 
 file "dominio.com.br"; 
};


---/var/named/dominio.com.br---------

$TTL 1D
@       IN      SOA     dns1.dominio.com.br.    email.dominio.com.br. (
                        2003061113      ; serial
                        4H              ; refresh
                        2H              ; retry
                        2W              ; expire
                        1D )            ; minimum
                NS      dns1.dominio.com.br.
                NS      dns2.dominio.com.br.
                MX      10 mail.dominio.com.br.
$ORIGIN dominio.com.br.
                A       1.2.3.4
www             A       1.2.3.4
mail            A       1.2.3.4