Why does bind not resolve PTR?

Question

Domain Name System

Forward Lookup Zone

$TTL    604800
@       IN      SOA     usrv.sandbox.corp. root.usrv.sandbox.corp. (
                              2         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
@       IN      NS      usrv.sandbox.corp.
@       IN      A       192.168.99.50
@       IN      AAAA    ::1
usrv    IN      A       192.168.99.50
nnm     IN      A       192.168.99.51

Reverse Lookup Zone

$TTL    604800
@       IN      SOA     usrv.sandbox.corp. root.usrv.sandbox.corp. (
                              2         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
@       IN      NS      usrv.sandbox.corp.
50      IN      PTR     usrv.sabdbox.corp.
51      IN      PTR     nnm.sandbox.corp.

Addresses from the forward lookup zone resolve perfectly

host nnm
nnm.sandbox.corp has address 192.168.99.51

Only the DNS server itself is resolved from the reverse lookup zone

host 192.168.99.50
50.99.168.192.in-addr.arpa domain name pointer usrv.sandbox.corp.
50.99.168.192.in-addr.arpa domain name pointer usrv.
50.99.168.192.in-addr.arpa domain name pointer usrv.local.

other records are not processed

host 192.168.99.51
Host 51.99.168.192.in-addr.arpa. not found: 3(NXDOMAIN)

error in log

usrv systemd-resolved[599]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature level UDP.

Answer 1

@       IN      SOA     ns1.ks03.ru. info.ks03.ru. (
                        2020021701       ; serial, todays date + todays serial #
                        7200              ; refresh, seconds
                        540              ; retry, seconds
                        1209600              ; expire, seconds
                        86400 )            ; minimum, seconds
;

2112.topexpert.pro. 3600 A        95.216.243.254
mx 3600 A        95.216.243.254
www 3600 A        95.216.243.254
mail.2112.topexpert.pro. 3600      CNAME        domain.mail.yandex.net.
2112.topexpert.pro. 3600      MX    10   mx.yandex.net.
2112.topexpert.pro. 3600      MX    20   mx.2112.topexpert.pro.
2112.topexpert.pro. 3600      NS        ns1.ks03.ru.
2112.topexpert.pro. 3600      NS        ns2.ks03.ru.
254.243.216.95.in-addr.arpa  3600      PTR        2112.topexpert.pro
2112.topexpert.pro. 3600      TXT        "v=spf1 ip4:95.216.243.254 ip4:95.216.243.198 include:_spf.yandex.net ~all"

As you can see, everything is the same, the
difference is that the PTR is reverse !!!! and it is not enough just to register them in the DNS, because they are "reverse"
and they indicate on the side of your hosting provider and not on your DNS server
. In your DNS, they are only confirmed!
Contact the support service so that they indicate the reverse PTR
For example, at hetzner they can be specified in the place where you order the server,

but in 99% it is through the support service
also do not forget to specify DKIM - requires
the DMARC daemon - requires DKIM but the SPF text entry itself
is purely text entry
as well as new CAA

Answer 2

The problem was solved by catching a syntax error