root@server:~# apt install bind9

root@server:~# cat /etc/bind/named.conf

options {
        directory "/var/cache/bind";

        allow-recursion { any; };
        
        forwarders {
                172.16.1.254;
        };
        empty-zones-enable no;
};

view "inside" {
        match-clients {
//            192.168.X/24;
//            127/8;
              0/0;
        };
        zone "corpX.un" {
                type master;
                file "/etc/bind/corpX.un";
        };
};

view "outside" {
        zone "corpX.un" {
                type master;
                file "/etc/bind/corpX.un.out";
        };
};

server# cat /etc/bind/corpX.un

$TTL      3h
@         SOA     ns root.ns  1 1d 12h 1w 3h
          NS      ns

;ns        A       192.168.X.10
;gate      A       192.168.X.1
;server    A       192.168.X.10

;ftp      CNAME   server
;www      CNAME   server
;nfs      CNAME   server
;mail     CNAME   server
;ntp	  CNAME   gate

;router    A       192.168.X.1
;switch    A       192.168.X.3

;ns        A       192.168.X.1
;ns        A       192.168.X.2
;node1     A       192.168.X.1
;node2     A       192.168.X.2
;gate      A       192.168.X.254

;_sip._udp           SRV     0 0 5060 server

;_xmpp-client._tcp   SRV     0 0 5222 server

;_kerberos._udp      SRV     01 00 88 server
;_kerberos._tcp      SRV     01 00 88 server
;_kerberos           TXT     CORPX.UN

server# cat corpX.un.out

$TTL      3h
@         SOA     ns root.ns  1 1d 12h 1w 3h
          NS      ns

ns        A       172.16.1.X

;gate      A       172.16.1.X
;server    A       172.16.1.X

;ftp      CNAME   server
;www      CNAME   server
;mail     CNAME   server

;_sip._udp           SRV     00 00 6050 server

server# named-checkconf -z

[server:~] # cat /etc/rc.conf

...
named_enable="YES"

[server:~] # service named start

root@server:~# service bind9 restart

debian11# service named restart

# cat /etc/resolv.conf

search corpX.un
nameserver 192.168.X.10

# host ns

# host ya.ru

ns.isp.un# cat named.conf

...
zone "un" {
        type master;
        file "un";
};
...
zone "corp1.un" IN {type forward;forwarders {192.168.1.10;};};
...
zone "corp12.un" IN {type forward;forwarders {192.168.12.10;};};

//zone "corp1.un" IN {type forward;forwarders {172.16.1.1;};};
...
//zone "corp12.un" IN {type forward;forwarders {172.16.1.12;};};
...

gate.isp.un# cat un

...
ns1            A       192.168.1.10
...
ns12           A       192.168.12.10

;ns1           A       172.16.1.1
...
;ns12          A       172.16.1.12
...
corp1          NS      ns1
...
corp12         NS      ns12
...

[server:~] # pkg install bind99

[server:~] # cat /usr/local/etc/namedb/named.conf

options {
        directory       "/usr/local/etc/namedb/working";
        pid-file        "/var/run/named/pid";

        allow-recursion { any; };
        
        forwarders {
                172.16.1.254;
        };
};

view "inside" {
        match-clients {
//              192.168.X/24;
//              127/8;
                0/0;
        };
        zone "corpX.un" {
                type master;
                file "/usr/local/etc/namedb/master/corpX.un";
        };
};

view "outside" {
        zone "corpX.un" {
                type master;
                file "/usr/local/etc/namedb/master/corpX.un.out";
        };
};