This document summarizes changes since the last production release on
   the BIND 9.11 branch. Please see the CHANGES file for a further list of
   bug fixes and other changes.


   The latest versions of BIND 9 software can always be found at There you will find additional
   information about each release, source code, and pre-compiled versions
   for Microsoft Windows operating systems.

New DNSSEC Root Key

   ICANN is in the process of introducing a new Key Signing Key (KSK) for
   the global root zone. BIND has multiple methods for managing DNSSEC
   trust anchors, with somewhat different behaviors. If the root key is
   configured using the managed-keys statement, or if the pre-configured
   root key is enabled by using dnssec-validation auto, then BIND can keep
   keys up to date automatically. Servers configured in this way will roll
   seamlessly to the new key when it is published in the root zone.
   However, keys configured using the trusted-keys statement are not
   automatically maintained. If your server is performing DNSSEC
   validation and is configured using trusted-keys, you are advised to
   change your configuration before the root zone begins signing with the
   new KSK. This is currently scheduled for October 11, 2017.

   This release includes an updated version of the bind.keys file
   containing the new root key. This file can also be downloaded from .

License Change

   With the release of BIND 9.11.0, ISC changed to the open source license
   for BIND from the ISC license to the Mozilla Public License (MPL 2.0).

   The MPL-2.0 license requires that if you make changes to licensed
   software (e.g. BIND) and distribute them outside your organization,
   that you publish those changes under that same license. It does not
   require that you publish or disclose anything other than the changes
   you made to our software.

   This new requirement will not affect anyone who is using BIND without
   redistributing it, nor anyone redistributing it without changes,
   therefore this change will be without consequence for most individuals
   and organizations who are using BIND.

   Those unsure whether or not the license change affects their use of
   BIND, or who wish to discuss how to comply with the license may contact
   ISC at

Security Fixes

     * rndc "" could trigger an assertion failure in named. This flaw is
       disclosed in (CVE-2017-3138). [RT #44924]
     * Some chaining (i.e., type CNAME or DNAME) responses to upstream
       queries could trigger assertion failures. This flaw is disclosed in
       CVE-2017-3137. [RT #44734]
     * dns64 with break-dnssec yes; can result in an assertion failure.
       This flaw is disclosed in CVE-2017-3136. [RT #44653]
     * If a server is configured with a response policy zone (RPZ) that
       rewrites an answer with local data, and is also configured for
       DNS64 address mapping, a NULL pointer can be read triggering a
       server crash. This flaw is disclosed in CVE-2017-3135. [RT #44434]
     * A coding error in the nxdomain-redirect feature could lead to an
       assertion failure if the redirection namespace was served from a
       local authoritative data source such as a local zone or a DLZ
       instead of via recursive lookup. This flaw is disclosed in
       CVE-2016-9778. [RT #43837]
     * named could mishandle authority sections with missing RRSIGs,
       triggering an assertion failure. This flaw is disclosed in
       CVE-2016-9444. [RT #43632]
     * named mishandled some responses where covering RRSIG records were
       returned without the requested data, resulting in an assertion
       failure. This flaw is disclosed in CVE-2016-9147. [RT #43548]
     * named incorrectly tried to cache TKEY records which could trigger
       an assertion failure when there was a class mismatch. This flaw is
       disclosed in CVE-2016-9131. [RT #43522]
     * It was possible to trigger assertions when processing responses
       containing answers of type DNAME. This flaw is disclosed in
       CVE-2016-8864. [RT #43465]
     * Added the ability to specify the maximum number of records
       permitted in a zone (max-records #;). This provides a mechanism to
       block overly large zone transfers, which is a potential risk with
       slave zones from other parties, as described in CVE-2016-6170. [RT

Feature Changes

     * dnstap now stores both the local and remote addresses for all
       messages, instead of only the remote address. The default output
       format for dnstap-read has been updated to include these addresses,
       with the initiating address first and the responding address
       second, separated by "-%gt;" or "%lt;-" to indicate in which
       direction the message was sent. [RT #43595]
     * Expanded and improved the YAML output from dnstap-read -y: it now
       includes packet size and a detailed breakdown of message contents.
       [RT #43622] [RT #43642]
     * If an ACL is specified with an address prefix in which the prefix
       length is longer than the address portion (for example,, named will now log a warning. In future releases this
       will be a fatal configuration error. [RT #43367]

Bug Fixes

     * A synthesized CNAME record appearing in a response before the
       associated DNAME could be cached, when it should not have been.
       This was a regression introduced while addressing CVE-2016-8864.
       [RT #44318]
     * named could deadlock if multiple changes to NSEC/NSEC3 parameters
       for the same zone were being processed at the same time. [RT
     * named could trigger an assertion when sending NOTIFY messages. [RT
     * Referencing a nonexistent zone in a response-policy statement could
       cause an assertion failure during configuration. [RT #43787]
     * rndc addzone could cause a crash when attempting to add a zone with
       a type other than master or slave. Such zones are now rejected. [RT
     * named could hang when encountering log file names with large
       apparent gaps in version number (for example, when files exist
       called "logfile.0", "logfile.1", and "logfile.1482954169"). This is
       now handled correctly. [RT #38688]
     * If a zone was updated while named was processing a query for
       nonexistent data, it could return out-of-sync NSEC3 records causing
       potential DNSSEC validation failure. [RT #43247]


     * The built-in root hints have been updated to include an IPv6
       address (2001:500:12::d0d) for G.ROOT-SERVERS.NET.

Miscellaneous Notes

     * Authoritative server support for the EDNS Client Subnet option
       (ECS), introduced in BIND 9.11.0, was based on an early version of
       the specification, and is now known to have incompatibilities with
       other ECS implementations. It is also inefficient, requiring a
       separate view for each answer, and is unable to correct for
       overlapping subnets in the configuration. It is intended for
       testing purposes but is not recommended for for production use.
       This was not made sufficiently clear in the documentation at the
       time of release.

End of Life

   The end of life for BIND 9.11 is yet to be determined but will not be
   before BIND 9.13.0 has been released for 6 months.

Thank You

   Thank you to everyone who assisted us in making this release possible.
   If you would like to contribute to ISC to assist us in continuing to
   make quality open source software, please visit our donations page at
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