Created attachment 1616227 [details]
/etc/named.conf

Description of problem:
BIND 9.9 from RHEL 7.6 behaves like this:

[root@tux ~]# rpm -q bind
bind-9.9.4-72.el7.x86_64
[root@tux ~]# 

[root@tux ~]# ss -lpn | grep :53
udp    UNCONN     0      0      127.0.0.1:53                    *:*                   users:(("named",pid=1323,fd=513),("named",pid=1323,fd=512))
tcp    LISTEN     0      10     127.0.0.1:53                    *:*                   users:(("named",pid=1323,fd=21))
[root@tux ~]# 

When now using the exactly same configuration file, BIND 9.11 from RHEL 7.7 behaves like this:

[root@tux ~]# rpm -q bind
bind-9.11.4-9.P2.el7.x86_64
[root@tux ~]# 

[root@tux ~]# ss -lpn | grep :53
udp    UNCONN     0      0      127.0.0.1:53                    *:*                   users:(("named",pid=1444,fd=513))
udp    UNCONN     0      0        :::53                   :::*                   users:(("named",pid=1444,fd=512))
tcp    LISTEN     0      10     127.0.0.1:53                    *:*                   users:(("named",pid=1444,fd=22))
tcp    LISTEN     0      10       :::53                   :::*                   users:(("named",pid=1444,fd=21))
[root@tux ~]# 

While I'm tempted to not call this a "regression" explicitly, because the world needs to use more IPv6 for sure, it still is a undocumented change that must be at least documented in the RHEL 7.7 release notes.

Version-Release number of selected component (if applicable):
bind-9.11.4-9.P2.el7.x86_64

How reproducible:
Always, see above and below.

Steps to Reproduce:
1. Install bind-9.9.4-72.el7.x86_64
2. Use attached configuration file for /etc/named.conf
3. systemctl start named
4. "ss -lpn | grep :53" outputs listening on 127.0.0.1:53
5. Update to bind-9.11.4-9.P2.el7.x86_64
6. Ensure /etc/named.conf configuration file remained unchanged
7. systemctl stop named; systemctl start named
8. "ss -lpn | grep :53" outputs listening on 127.0.0.1:53 AND [::]:53

Actual results:
BIND 9.11 listens on [::]:53 even it isn't configured to do so.

Expected results:
a) Document this new behaviour in the RHEL 7.7 release notes, or alternatively
b) Treat this new behaviour as regression and restore the old behaviour

Additional info:
While it seems a trivial issue, any unintended new listening on [::]:53 might break other daemons like in our use-case where Samba-AD/DC was listening on [::1]:53 which no longer worked because the port was consumed by BIND now.