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bind9/doc/notes/notes-current.rst
Matthijs Mekking e02ce9e833 Add notes and change entry for [#2434]
This concludes the serve-stale improvements.

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2021-02-08 16:09:36 +01:00

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Copyright (C) Internet Systems Consortium, Inc. ("ISC")
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, you can obtain one at https://mozilla.org/MPL/2.0/.
See the COPYRIGHT file distributed with this work for additional
information regarding copyright ownership.
Notes for BIND 9.16.12
----------------------
Security Fixes
~~~~~~~~~~~~~~
- None.
Known Issues
~~~~~~~~~~~~
- None.
New Features
~~~~~~~~~~~~
- When a secondary server receives a large incremental zone
transfer (IXFR), it can have a negative impact on query
performance while the incremental changes are applied to
the zone. To address this, ``named`` can now
limit the size of IXFR responses it sends in response to zone
transfer requests. If an IXFR response would be larger than an
AXFR of the entire zone, it will send an AXFR resonse instead.
This behavior is controlled by the ``max-ixfr-ratio``
option - a percentage value representing the ratio of IXFR size
to the size of a full zone transfer. This value cannot exceed
100%, which is also the default. [GL #1515]
- A new option, ``stale-answer-client-timeout``, has been added to
improve ``named``'s behavior with respect to serving stale data. The option
defines the amount of time ``named`` waits before attempting
to answer the query with a stale RRset from cache. If a stale answer
is found, ``named`` continues the ongoing fetches, attempting to
refresh the RRset in cache until the ``resolver-query-timeout`` interval is
reached.
The default value is ``1800`` (in milliseconds) and the maximum value is
bounded to ``resolver-query-timeout`` minus one second. A value of
``0`` immediately returns a cached RRset if available, and still
attempts a refresh of the data in cache.
The option can be disabled by setting the value to ``off`` or
``disabled``. It also has no effect if ``stale-answer-enable`` is
disabled. [GL #2247]
- When serve-stale is enabled and stale data is available, ``named`` now
returns stale answers upon encountering any unexpected error in the
query resolution process. This may happen, for example, if the
``fetches-per-server`` or ``fetches-per-zone`` limits are reached. In
this case, ``named`` attempts to answer DNS requests with stale data,
but does not start the ``stale-refresh-time`` window. [GL #2434]
Removed Features
~~~~~~~~~~~~~~~~
- None.
Feature Changes
~~~~~~~~~~~~~~~
- The SONAMEs for BIND 9 libraries now include the current BIND 9
version number, in an effort to tightly couple internal libraries with
a specific release. This change makes the BIND 9 release process both
simpler and more consistent while also unequivocally preventing BIND 9
binaries from silently loading wrong versions of shared libraries (or
multiple versions of the same shared library) at startup. [GL #2387]
- The default value of ``max-stale-ttl`` has been changed from 12 hours to 1
day and the default value of ``stale-answer-ttl`` has been changed from 1
second to 30 seconds, following RFC 8767 recommendations. [GL #2248]
- As part of an ongoing effort to use RFC 8499 terminology,
``primaries`` can now be used as a synonym for ``masters`` in
``named.conf``. Similarly, ``notify primary-only`` can now be used as
a synonym for ``notify master-only``. The output of ``rndc
zonestatus`` now uses ``primary`` and ``secondary`` terminology.
[GL #1948]
- When ``check-names`` is in effect, A records below an ``_spf``, ``_spf_rate``
and ``_spf_verify`` labels (which are employed by the ``exists`` SPF
mechanism defined inr:rfc:`7208` section 5.7/appendix D1) are no longer
reported as warnings/errors. [GL #2377]
Bug Fixes
~~~~~~~~~
- KASP incorrectly set signature validity to the value of the DNSKEY signature
validity. This is now fixed. [GL #2383]
- Previously, ``dnssec-keyfromlabel`` crashed when operating on an ECDSA key.
This has been fixed. [GL #2178]
- Named ``allow-update`` acls where broken in BIND 9.17.9 and BIND 9.16.11
preventing ``named`` starting. [GL #2413]
- When migrating to ``dnssec-policy``, BIND considered keys with the "Inactive"
and/or "Delete" timing metadata as possible active keys. This has been fixed.
[GL #2406]
- Fix the "three is a crowd" key rollover bug in ``dnssec-policy``. When keys
rolled faster than the time required to finish the rollover procedure, the
successor relation equation failed because it assumed only two keys were
taking part in a rollover. This could lead to premature removal of
predecessor keys. BIND 9 now implements a recursive successor relation, as
described in the paper "Flexible and Robust Key Rollover" (Equation (2)).
[GL #2375]