Problem:Reverse IP Lookup for Clients

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Problem:

There are clients in a network segment with a subnet of 21 in the IP range 192.168.178.0. In contrast to a 24 network, the specified reverse lookup zone here is only 192.168 and not 192.168.178. If an nslookup or a dig -x is now performed on the IP 192.168.178.20 for example, the zone reports back:

server can't find 20.178.168.192.in-addr.arpa: NXDOMAIN.

Why is the client not resolved correctly?

Investigation:

Because there are no pointer records for the respective client in the reverse zone of the 192.168.178 and therefore it cannot be resolved or found. The ptr_record is located in the 21 network of 192.168. as the client is certainly also located in this network segment and this should actually be queried and provide the expected output.

As example:
udm dns/ptr_record list --filter relativeDomainName=20*

DN: relativeDomainName=20.178,zoneName=168.192.in-addr.arpa,cn=dns,dc=ucs5schoolhejne,dc=intranet
  address: 20.178
  ip: 192.168.178.20
  ptr_record: dc5.ucs5schoolhejne.intranet.

Now check the Reverse Zone:
udm dns/reverse_zone list | less

DN: zoneName=168.192.in-addr.arpa,cn=dns,dc=ucs5schoolhejne,dc=intranet
  contact: root@ucs5schoolhejne.intranet.
  expire: 7 days
  nameserver: dc0.ucs5schoolhejne.intranet.
  refresh: 8 hours
  retry: 2 hours
  serial: 6
  subnet: 192.168
  ttl: 1 days
  zonettl: 3 hours

DN: zoneName=178.168.192.in-addr.arpa,cn=dns,dc=ucs5schoolhejne,dc=intranet
  contact: root@ucs5schoolhejne.intranet.
  expire: 7 days
  nameserver: dc0.ucs5schoolhejne.intranet.
  refresh: 8 hours
  retry: 2 hours
  serial: 1
  subnet: 192.168.178
  ttl: 1 days
  zonettl: 3 hours

Solution:

Remove the Reverse Zone with no existing PTR records, ensuring resolution uses the correct zone with valid PTR records, restart bind9 Service and try again the nslookup/dig -x for 192.168.178.29.

  1. udm dns/reverse_zone remove --dn zoneName=178.168.192.in-addr.arpa,cn=dns,dc=ucs5schoolhejne,dc=intranet
Object removed: zoneName=178.168.192.in-addr.arpa,cn=dns,dc=ucs5schoolhejne,dc=intranet

  1. systemctl restart bind9.service

  2. nslookup 192.168.178.20

20.178.168.192.in-addr.arpa     name = dc5.ucs5schoolhejne.intranet.