bind  9.12.4
About: BIND 9.12 implements the Domain Name System (DNS) protocols for the Internet. (see the Release Notes). Source code distribution.
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bind Documentation



  1. Introduction
  1. Reporting bugs and getting help
  1. Contributing to BIND
  1. BIND 9.12 features
  1. Building BIND
  1. macOS
  1. Dependencies
  1. Compile-time options
  1. Automated testing
  1. Documentation
  1. Change log
  1. Acknowledgments


BIND (Berkeley Internet Name Domain) is a complete, highly portable implementation of the DNS (Domain Name System) protocol.

The BIND name server, named, is able to serve as an authoritative name server, recursive resolver, DNS forwarder, or all three simultaneously. It implements views for split-horizon DNS, automatic DNSSEC zone signing and key management, catalog zones to facilitate provisioning of zone data throughout a name server constellation, response policy zones (RPZ) to protect clients from malicious data, response rate limiting (RRL) and recursive query limits to reduce distributed denial of service attacks, and many other advanced DNS features. BIND also includes a suite of administrative tools, including the dig and delv DNS lookup tools, nsupdate for dynamic DNS zone updates, rndc for remote name server administration, and more.

BIND 9 is a complete re-write of the BIND architecture that was used in versions 4 and 8. Internet Systems Consortium (, a 501(c)(3) public benefit corporation dedicated to providing software and services in support of the Internet infrastructure, developed BIND 9 and is responsible for its ongoing maintenance and improvement. BIND is open source software licenced under the terms of the Mozilla Public License, version 2.0.

For a summary of features introduced in past major releases of BIND, see the file HISTORY.

For a detailed list of changes made throughout the history of BIND 9, see the file [CHANGES](CHANGES). See below for details on the CHANGES file format.

For up-to-date release notes and errata, see

Reporting bugs and getting help

To report non-security-sensitive bugs or request new features, you may open an Issue in the BIND 9 project on the ISC GitLab server at

Please note that, unless you explicitly mark the newly created Issue as "confidential", it will be publicly readable. Please do not include any information in bug reports that you consider to be confidential unless the issue has been marked as such. In particular, if submitting the contents of your configuration file in a non-confidential Issue, it is advisable to obscure key secrets: this can be done automatically by using named-checkconf -px.

If the bug you are reporting is a potential security issue, such as an assertion failure or other crash in named, please do NOT use GitLab to report it. Instead, please send mail to

Professional support and training for BIND are available from ISC at

To join the BIND Users mailing list, or view the archives, visit

If you're planning on making changes to the BIND 9 source code, you may also want to join the BIND Workers mailing list, at

Contributing to BIND

ISC maintains a public git repository for BIND; details can be found at

Information for BIND contributors can be found in the following files:

  • General information: doc/dev/
  • BIND 9 code style: doc/dev/
  • BIND architecture and developer guide: doc/dev/

Patches for BIND may be submitted as Merge Requests in the ISC GitLab server at at

By default, external contributors don't have ability to fork BIND in the GitLab server, but if you wish to contribute code to BIND, you may request permission to do so. Thereafter, you can create git branches and directly submit requests that they be reviewed and merged.

If you prefer, you may also submit code by opening a GitLab Issue and including your patch as an attachment, preferably generated by git format-patch.

BIND 9.12 features

BIND 9.12.0 is the newest development branch of BIND 9. It includes a number of changes from BIND 9.11 and earlier releases. New features include:

  • named and related libraries have been substantially refactored for improved query performance – particularly on delegation heavy zones – and for improved readability, maintainability, and testability.
  • Code implementing the name server query processing logic has been moved into a new libns library, for easier testing and use in tools other than named.
  • Cached, validated NSEC and other records can now be used to synthesize NXDOMAIN responses.
  • The DNS Response Policy Service API (DNSRPS) is now supported.
  • Setting ‘'max-journal-size default’` now limits the size of journal files to twice the size of the zone.
  • dnstap-read -x prints a hex dump of the wire format of each logged DNS message.
  • dnstap output files can now be configured to roll automatically when reaching a given size.
  • Log file timestamps can now also be formatted in ISO 8601 (local) or ISO 8601 (UTC) formats.
  • Logging channels and dnstap output files can now be configured to use a timestamp as the suffix when rolling to a new file.
  • ‘'named-checkconf -l’lists zones found innamed.conf`.
  • Added support for the EDNS Padding and Keepalive options.
  • 'new-zones-directory' option sets the location where the configuration data for zones added by rndc addzone is stored.
  • The default key algorithm in rndc-confgen is now hmac-sha256.
  • filter-aaaa-on-v4 and filter-aaaa-on-v6 options are now available by default without a configure option.
  • The obsolete isc-hmac-fixup command has been removed.

BIND 9.12.1

BIND 9.12.1 is a maintenance release.

BIND 9.12.2

BIND 9.12.2 is a maintenance release, and addresses security vulnerabilities disclosed in CVE-2018-5736, CVE-2018-5737 and CVE-2018-5738.

BIND 9.12.3

BIND 9.12.3 is a maintenance release, and also addresses CVE-2018-5741 by correcting faulty documentation and introducing the following new feature:

  • New krb5-selfsub and ms-selfsub rule types for update-policy statements allow updating of subdomains based on a Kerberos or Active Directory machine principal.

BIND 9.12.4

BIND 9.12.4 is a maintenance release, and addresses the security vulnerabilities disclosed in CVE-2018-5744, CVE-2018-5745, and CVE-2019-6465.

Building BIND

BIND requires a UNIX or Linux system with an ANSI C compiler, basic POSIX support, and a 64-bit integer type. Successful builds have been observed on many versions of Linux and UNIX, including RedHat, Fedora, Debian, Ubuntu, SuSE, Slackware, FreeBSD, NetBSD, OpenBSD, Mac OS X, Solaris, HP-UX, AIX, SCO OpenServer, and OpenWRT.

BIND is also available for Windows 2008 and higher. See win32utils/readme1st.txt for details on building for Windows systems.

To build on a UNIX or Linux system, use:

    $ ./configure
    $ make

If you're planning on making changes to the BIND 9 source, you should run make depend. If you're using Emacs, you might find make tags helpful.

Several environment variables that can be set before running configure will affect compilation:

Variable Description
CC The C compiler to use. configure tries to figure out the right one for supported systems.
CFLAGS C compiler flags. Defaults to include -g and/or -O2 as supported by the compiler. Please include '-g' if you need to set CFLAGS.
STD_CINCLUDES System header file directories. Can be used to specify where add-on thread or IPv6 support is, for example. Defaults to empty string.
STD_CDEFINES Any additional preprocessor symbols you want defined. Defaults to empty string. For a list of possible settings, see the file OPTIONS.
LDFLAGS Linker flags. Defaults to empty string.
BUILD_CC Needed when cross-compiling: the native C compiler to use when building for the target system.
BUILD_CFLAGS Optional, used for cross-compiling


Building on macOS assumes that the "Command Tools for Xcode" is installed. This can be downloaded from or if you have Xcode already installed you can run "xcode-select --install". This will add /usr/include to the system and install the compiler and other tools so that they can be easily found.


Portions of BIND that are written in Python, including dnssec-keymgr, dnssec-coverage, dnssec-checkds, and some of the system tests, require the 'argparse' and 'ply' modules to be available. 'argparse' is a standard module as of Python 2.7 and Python 3.2. 'ply' is available from

Compile-time options

To see a full list of configuration options, run configure --help.

On most platforms, BIND 9 is built with multithreading support, allowing it to take advantage of multiple CPUs. You can configure this by specifying --enable-threads or --disable-threads on the configure command line. The default is to enable threads, except on some older operating systems on which threads are known to have had problems in the past. (Note: Prior to BIND 9.10, the default was to disable threads on Linux systems; this has now been reversed. On Linux systems, the threaded build is known to change BIND's behavior with respect to file permissions; it may be necessary to specify a user with the -u option when running named.)

To build shared libraries, specify --with-libtool on the configure command line.

For the server to support DNSSEC, you need to build it with crypto support. To use OpenSSL, you should have OpenSSL 1.0.2e or newer installed. If the OpenSSL library is installed in a nonstandard location, specify the prefix using "--with-openssl=<PREFIX>" on the configure command line. To use a PKCS#11 hardware service module for cryptographic operations, specify the path to the PKCS#11 provider library using "--with-pkcs11=<PREFIX>", and configure BIND with "--enable-native-pkcs11".

To support the HTTP statistics channel, the server must be linked with at least one of the following: libxml2 or json-c If these are installed at a nonstandard location, specify the prefix using --with-libxml2=/prefix or --with-libjson=/prefix.

To support compression on the HTTP statistics channel, the server must be linked against libzlib. If this is installed in a nonstandard location, specify the prefix using --with-zlib=/prefix.

To support storing configuration data for runtime-added zones in an LMDB database, the server must be linked with liblmdb. If this is installed in a nonstandard location, specify the prefix using "with-lmdb=/prefix".

To support GeoIP location-based ACLs, the server must be linked with libGeoIP. This is not turned on by default; BIND must be configured with "--with-geoip". If the library is installed in a nonstandard location, use specify the prefix using "--with-geoip=/prefix".

For DNSTAP packet logging, you must have installed libfstrm and libprotobuf-c, and BIND must be configured with --enable-dnstap.

Certain compiled-in constants and default settings can be increased to values better suited to large servers with abundant memory resources (e.g, 64-bit servers with 12G or more of memory) by specifying --with-tuning=large on the configure command line. This can improve performance on big servers, but will consume more memory and may degrade performance on smaller systems.

On some platforms it is necessary to explicitly request large file support to handle files bigger than 2GB. This can be done by using --enable-largefile on the configure command line.

Support for the "fixed" rrset-order option can be enabled or disabled by specifying --enable-fixed-rrset or --disable-fixed-rrset on the configure command line. By default, fixed rrset-order is disabled to reduce memory footprint.

If your operating system has integrated support for IPv6, it will be used automatically. If you have installed KAME IPv6 separately, use --with-kame[=PATH] to specify its location.

The --enable-querytrace option causes named to log every step of processing every query. This should only be enabled when debugging, because it has a significant negative impact on query performance.

make install will install named and the various BIND 9 libraries. By default, installation is into /usr/local, but this can be changed with the --prefix option when running configure.

You may specify the option --sysconfdir to set the directory where configuration files like named.conf go by default, and --localstatedir to set the default parent directory of run/ For backwards compatibility with BIND 8, --sysconfdir defaults to /etc and --localstatedir defaults to /var if no --prefix option is given. If there is a --prefix option, sysconfdir defaults to $prefix/etc and localstatedir defaults to $prefix/var.

Automated testing

A system test suite can be run with make test. The system tests require you to configure a set of virtual IP addresses on your system (this allows multiple servers to run locally and communicate with one another). These IP addresses can be configured by running the command bin/tests/system/ up as root.

Some tests require Perl and the Net::DNS and/or IO::Socket::INET6 modules, and will be skipped if these are not available. Some tests require Python and the 'dnspython' module and will be skipped if these are not available. See bin/tests/system/README for further details.

Unit tests are implemented using the CMocka unit testing framework. To build them, use configure --with-cmocka. Execution of tests is done by the Kyua test execution engine; if the kyua command is available, then unit tests can be run via make test or make unit.


The BIND 9 Administrator Reference Manual is included with the source distribution, in DocBook XML, HTML and PDF format, in the doc/arm directory.

Some of the programs in the BIND 9 distribution have man pages in their directories. In particular, the command line options of named are documented in bin/named/named.8.

Frequently (and not-so-frequently) asked questions and their answers can be found in the ISC Knowledge Base at

Additional information on various subjects can be found in other README files throughout the source tree.

Change log

A detailed list of all changes that have been made throughout the development BIND 9 is included in the file CHANGES, with the most recent changes listed first. Change notes include tags indicating the category of the change that was made; these categories are:

Category Description
[func] New feature
[bug] General bug fix
[security] Fix for a significant security flaw
[experimental] Used for new features when the syntax or other aspects of the design are still in flux and may change
[port] Portability enhancement
[maint] Updates to built-in data such as root server addresses and keys
[tuning] Changes to built-in configuration defaults and constants to improve performance
[performance] Other changes to improve server performance
[protocol] Updates to the DNS protocol such as new RR types
[test] Changes to the automatic tests, not affecting server functionality
[cleanup] Minor corrections and refactoring
[doc] Documentation
[contrib] Changes to the contributed tools and libraries in the 'contrib' subdirectory
[placeholder] Used in the master development branch to reserve change numbers for use in other branches, e.g. when fixing a bug that only exists in older releases

In general, [func] and [experimental] tags will only appear in new-feature releases (i.e., those with version numbers ending in zero). Some new functionality may be backported to older releases on a case-by-case basis. All other change types may be applied to all currently-supported releases.


  • The original development of BIND 9 was underwritten by the following organizations:
      Sun Microsystems, Inc.
      Hewlett Packard
      Compaq Computer Corporation
      Process Software Corporation
      Silicon Graphics, Inc.
      Network Associates, Inc.
      U.S. Defense Information Systems Agency
      USENIX Association
      Stichting NLnet - NLnet Foundation
      Nominum, Inc.
  • This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit.
  • This product includes cryptographic software written by Eric Young (
  • This product includes software written by Tim Hudson (