reverse_zone

$TTL    86400
@       IN      SOA     cloudx.mks. root.cloudx.mks. (
                2018092501      ;Serial
                3600            ;Refresh
                1800            ;Retry
                604800          ;Expire
                86400           ;Minimum TTL
)

        IN      NS      ns1.cloudx.mks.
        IN      NS      ns2.cloudx.mks.
@       IN      A       192.168.56.50
ns1     IN      A       192.168.56.50
ns2     IN      A       192.168.56.50
50      IN      PTR     cloudx.mks.
50      IN      PTR     blog.cloudx.mks.