[Samba] Conflict entries in DNS with DHCP and dynamic DNS updates 

Samba Fan sambafan at outlook.de
Thu Feb 18 18:16:00 UTC 2021

It is about DNS updates through the ISC DHCP server failover cluster in a Samba 4 Active Directory environment. I have implemented this as described in the Samba wiki (https://wiki.samba.org/index.php/Configure_DHCP_to_update_DNS_records_with_BIND9).

The failover works fine from the outside. However, the script (I use version 0.9.2) is executed on both servers at the same time (event "on commit"). This has the effect that a DNS record is created on both servers at the same time, if it did not already exist. This creates "conflict records" in both the forward and reverse zones, which the DNS then resolves so that one of them appears as hostname\nCNF:UID or ip-address\nCNF:UID in the forward zone or reverse zone, respectively.

The name resolution in both directions works, because the correct entries are in the DNS. However, the "useless" CNF entries remain. What can I set or check? How can I prevent these CNF entries? I have not found an answer yet.

These are the operating systems and versions of the software packages involved:
Server operating system: Ubuntu 16.04.7 LTS
Samba: Version 4.3.11-Ubuntu
DNS: BIND 9.10.3-P4-Ubuntu
DHCP: ISC DHCP Server version 4.3.3
Operating system of DHCP clients: Windows 10 1909 (DHCP updates by clients are disabled)

Regards, Sambafan

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