Configure Zone Files for each Zone set in [named.conf].
Replace Network or Domain name on the example below to your own environment.

[1] Create zone files that servers resolve IP address from Domain name.

The example below uses Internal network [10.0.0.0/24], Domain name [local].
Replace to your own environment.

[root@soncq ~]# vi /var/named/soncq.local.lan
$TTL 86400
@   IN  SOA     soncq.local. root.local. (
        # any numerical values are OK for serial number but
        # recommendation is [YYYYMMDDnn] (update date + number)
        2021022401  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
        # define Name Server
        IN  NS      soncq.local.
        # define Name Server's IP address
        IN  A       10.0.0.30
        # define Mail Exchanger Server
        IN  MX 10   soncq.local.

# define each IP address of a hostname
soncq     IN  A       10.0.0.30
www     IN  A       10.0.0.31

[2] Create zone files that servers resolve Domain name from IP address.

The example below uses Internal network [10.0.0.0/24], Domain name [srv.world].
Replace to your own environment.

[root@soncq ~]# vi /var/named/0.0.10.db
$TTL 86400
@   IN  SOA     soncq.local. root.local. (
        2021022401  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
        # define Name Server
        IN  NS      soncq.local.

# define each hostname of an IP address
30      IN  PTR     soncq.local.
31      IN  PTR     www.local

[3] Next, Start BIND and Verify Name or Address Resolution, refer to here.