Release Notes for BIND Version 9.12.0a1


BIND 9.12.0 is a new feature release of BIND, still under development. This document summarizes new features and functional changes that have been introduced on this branch. With each development release leading up to the final BIND 9.12.0 release, this document will be updated with additional features added and bugs fixed.


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.

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 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

Windows XP No Longer Supported

As of BIND 9.11.2, Windows XP is no longer a supported platform for BIND, and Windows XP binaries are no longer available for download from ISC.

Security Fixes

  • None.

New Features

  • Many aspects of named have been modified to improve query performance, and in particular, performance for delegation-heavy zones:

    • The additional cache ("acache") was found not to significantly improve performance and has been removed; the acache-enable and acache-cleaning-interval options are now deprecated.

    • In place of the acache, named can now use a glue cache to speed up retrieval of glue records when sending delegation responses. Unlike acache, this feature is on by default; use glue-cache no; to disable it.

    • The additional-from-cache and additional-from-auth options have been deprecated.

    • minimal-responses is now set to yes by default.

    • Several functions have been refactored to improve performance, including name compression, owner name case restoration, hashing, and buffers.

  • Several areas of code have been refactored for improved readability, maintainability, and testability:

    • The named query logic implemented in query_find() has been split into smaller functions with a context structure to maintain state between them, and extensive comments have been added. [RT #43929]

    • Similarly the iterative query logic implemented in resquery_response() function has been split into smaller functions and comments added. [RT #45362]

  • Code implementing name server query processing has been moved from named to an external library, libns. This will make it easier to write unit tests for the code, or to link it into new tools. [RT #45186]

  • named can now synthesize NXDOMAIN responses from cached DNSSEC-verified records returned in negative or wildcard responses. This will reduce query loads on authoritative servers for signed domains: if existing cached records can be used by the resolver to determine that a name does not exist in the authorittive domain, then no query needs to be sent.

    This behavior is controlled by the new named.conf option synth-from-dnssec. It is enabled by default.

    Note: This initial implementation can only synthesize NXDOMAIN responses, from NSEC records. Support for NODATA responses, wilcard responses, and NSEC3 records will be added soon.

  • The DNS Response Policy Service (DNSRPS) API, a mechanism to allow named to use an external response policy provider, is now supported. (One example of such a provider is "FastRPZ" from Farsight Security, Inc.) This allows the same types of policy filtering as standard RPZ, but can reduce the workload for named, particularly when using large and frequently-updated policy zones. It also enables named to share response policy providers with other DNS implementations such as Unbound.

    This feature is avaiable if BIND is built with configure --enable-dnsrps, if a DNSRPS provider is installed, and if dnsrps-enable is set to "yes" in named.conf. Standard built-in RPZ is used otherwise.

    Thanks to Vernon Schryver and Farsight Security for the contribution. [RT #43376]

  • Setting max-journal-size to default limits journal sizes to twice the size of the zone contents. This can be overridden by setting max-journal-size to unlimited or to an explicit value up to 2G. Thanks to Tony Finch for the contribution. [RT #38324]

  • dnstap logfiles can now be configured to automatically roll when they reach a specified size. If dnstap-output is configured with mode file, then it can take optional size and versions key-value arguments to set the logfile rolling parameters. (These have the same semantics as the corresponding options in a logging channel statement.) [RT #44502]

  • Logging channels and dnstap-output files can now be configured with a suffix option, set to either increment or timestamp, indicating whether log files should be given incrementing suffixes when they roll over (e.g., logfile.0, .1, .2, etc) or suffixes indicating the time of the roll. The default is increment. [RT #42838]

  • The print-time option in the logging configuration can now take arguments local, iso8601 or iso8601-utc to indicate the format in which the date and time should be logged. For backward compatibility, yes is a synonym for local. [RT #42585]

  • nsupdate and rndc now accepts command line options -4 and -6 which force using only IPv4 or only IPv6, respectively. [RT #45632]

  • nsec3hash -r ("rdata order") takes arguments in the same order as they appear in NSEC3 or NSEC3PARAM records. This makes it easier to generate an NSEC3 hash using values cut and pasted from an existing record. Thanks to Tony Finch for the contribution. [RT #45183]

  • The new-zones-directory option allows named to store configuration parameters for zones added via rndc addzone in a location other than the working directory. Thanks to Petr Menšík of Red Hat for the contribution. [RT #44853]

  • The dnstap-read -x option prints a hex dump of the wire format DNS message encapsulated in each dnstap log entry. [RT #44816]

  • The host -A option returns most records for a name, but omits types RRSIG, NSEC and NSEC3.

  • dig +ednsopt now accepts the names for EDNS options in addition to numeric values. For example, an EDNS Client-Subnet option could be sent using dig +ednsopt=ecs:.... Thanks to John Worley of Secure64 for the contribution. [RT #44461]

  • Added support for the EDNS TCP Keepalive option (RFC 7828); this allows negotiation of longer-lived TCP sessions to reduce the overhead of setting up TCP for individual queries. [RT #42126]

  • Added support for the EDNS Padding option (RFC 7830), which obfuscates packet size analysis when DNS queries are sent over an encrypted channel. [RT #42094]

  • rndc commands which refer to zone names can now reference a zone of type redirect by using the special zone name "-redirect". (Previously this was not possible because redirect zones always have the name ".", which can be ambiguous.)

    In the event you need to manipulate a zone actually called "-redirect", use a trailing dot: "-redirect."

    Note: This change does not appply to the rndc addzone or rndc modzone commands.

  • named-checkconf -l lists the zones found in named.conf. [RT #43154]

  • Query logging now includes the ECS option, if one was present in the query, in the format "[ECS address/source/scope]".

Protocol Changes

  • BIND can now use the Ed25519 and Ed448 Edwards Curve DNSSEC signing algorithms described in RFC 8080. Note, however, that these algorithms must be supported in OpenSSL; currently they are only available in the development branch of OpenSSL at [RT #44696]

  • EDNS KEY TAG options are verified and printed.

Feature Changes

  • The lightweight resolver daemon and library (lwresd and liblwres) have been removed. [RT #45186]

  • dnssec-keygen no longer has default algorithm settings. It is necessary to explicitly specify the algorithm on the command line with the -a option when generating keys. This may cause errors with existing signing scripts if they rely on current defaults. The intent is to reduce the long-term cost of transitioning to newer algorithms in the event of RSASHA1 being deprecated. [RT #44755]

  • dig +sigchase and related options +trusted-keys and +topdown have been removed. delv is now the recommended command for looking up records with DNSSEC validation. [RT #42793]

  • The Response Policy Zone (RPZ) implementation has been substantially refactored: updates to the RPZ summary database are no longer directly performed by the zone database but by a separate function that is called when a policy zone is updated. This improves both performance and reliability when policy zones receive frequent updates. Summary database updates can be rate-limited by using the min-update-interval option in a response-policy statement. [RT #43449]

  • 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]

  • Threads in named are now set to human-readable names to assist debugging on operating systems that support that. Threads will have names such as "isc-timer", "isc-sockmgr", "isc-worker0001", and so on. This will affect the reporting of subsidiary thread names in ps and top, but not the main thread. [RT #43234]

  • If an ACL is specified with an address prefix in which the prefix length is longer than the address portion (for example,, it will now be treated as a fatal error during configuration. [RT #43367]

  • dig now warns about .local queries which are reserved for Multicast DNS. [RT #44783]

  • The view associated with the query is now logged unless it it is "_default/IN" or "_dnsclient/IN" when logging DNSSEC validator messages.

  • Multiple cookie-secret clauses are now supported. The first cookie-secret in named.conf is used to generate new server cookies. Any others are used to accept old server cookies or those generated by other servers using the matching cookie-secret.

Bug Fixes

  • None.

End of Life

The end of life for BIND 9.12 is yet to be determined but will not be before BIND 9.14.0 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