Expand blackhole description

Clarify the behavior of negated addresses within the `blackhole`
statement to prevent common configuration misunderstandings.

(cherry picked from commit 2b23c7011e)
This commit is contained in:
Ondřej Surý 2026-02-26 17:13:04 +01:00 committed by Mark Andrews (GitLab job 7007005)
parent 2439e306a5
commit 22aa753e8c

View file

@ -3066,6 +3066,18 @@ for details on how to specify IP address lists.
from or or cannot use to resolve a query. Queries from these addresses are not
responded to. The default is ``none``.
When configuring this list, note that BIND evaluates Access Control Lists
sequentially (first match wins). A common misconception is that the directive
``!address;`` blocks everything except that address. In reality, it only
explicitly exempts ``address`` from the blackhole; all other IP addresses
reach the end of the list without matching, meaning they are also not
blackholed.
To successfully blackhole all traffic *except* specific addresses, you must
explicitly catch the remaining traffic with ``any;`` at the end of the list.
For example: ``!address; any;``
.. namedconf:statement:: no-case-compress
:tags: server
:short: Specifies a list of addresses that require case-insensitive compression in responses.