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 1. Introduction
 2. Reporting bugs and getting help
 3. Contributing to BIND
 4. BIND 9.11 features
 5. Building BIND
 6. macOS
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 7. Dependencies
 8. Compile-time options
 9. Automated testing
10. Documentation
11. Change log
12. Acknowledgments
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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
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source software licenced under the terms of ISC License for all versions
up to and including BIND 9.10, and the Mozilla Public License version 2.0
for all subsequent verisons.
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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. See below for details on the CHANGES file format.

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

Reporting bugs and getting help

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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 https://

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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
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named-checkconf -px.

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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

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Professional support and training for BIND are available from ISC at

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

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
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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/

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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

BIND 9.11 features

BIND 9.11.0 includes a number of changes from BIND 9.10 and earlier
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releases. New features include:

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  * Added support for Catalog Zones, a new method for provisioning
    servers: a list of zones to be served is stored in a DNS zone, along
    with their configuration parameters. Changes to the catalog zone are
    propagated to slaves via normal AXFR/IXFR, whereupon the zones that
    are listed in it are automatically added, deleted or reconfigured.
  * Added support for "dnstap", a fast and flexible method of capturing
    and logging DNS traffic.
  * Added support for "dyndb", a new API for loading zone data from an
    external database, developed by Red Hat for the FreeIPA project.
  * "fetchlimit" quotas are now compiled in by default. These are for the
    use of recursive resolvers that are are under high query load for
    domains whose authoritative servers are nonresponsive or are
    experiencing a denial of service attack:
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      + fetches-per-server limits the number of simultaneous queries that
        can be sent to any single authoritative server. The configured
        value is a starting point; it is automatically adjusted downward
        if the server is partially or completely non-responsive. The
        algorithm used to adjust the quota can be configured via the
        "fetch-quota-params" option.
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      + fetches-per-zone limits the number of simultaneous queries that
        can be sent for names within a single domain. (Note: Unlike
        fetches-per-server, this value is not self-tuning.)
      + New stats counters have been added to count queries spilled due to
        these quotas.
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  * Added a new dnssec-keymgr key mainenance utility, which can generate
    or update keys as needed to ensure that a zone's keys match a defined
    DNSSEC policy.
  * The experimental "SIT" feature in BIND 9.10 has been renamed "COOKIE"
    and is no longer optional. EDNS COOKIE is a mechanism enabling clients
    to detect off-path spoofed responses, and servers to detect
    spoofed-source queries. Clients that identify themselves using COOKIE
    options are not subject to response rate limiting (RRL) and can
    receive larger UDP responses.
  * SERVFAIL responses can now be cached for a limited time (defaulting to
    1 second, with an upper limit of 30). This can reduce the frequency of
    retries when a query is persistently failing.
  * Added an nsip-wait-recurse switch to RPZ. This causes NSIP rules to be
    skipped if a name server IP address isn't in the cache yet; the
    address will be looked up and the rule will be applied on future
  * Added a Python RNDC module. This allows multiple commands to sent over
    a persistent RNDC channel, which saves time.
  * The controls block in named.conf can now grant read-only rndc access
    to specified clients or keys. Read-only clients could, for example,
    check rndc status but could not reconfigure or shut down the server.
  * rndc commands can now return arbitrarily large amounts of text to the
  * The zone serial number of a dynamically updatable zone can now be set
    via rndc signing -serial <number> <zonename>. This allows
    inline-signing zones to be set to a specific serial number.
  * The new rndc nta command can be used to set a Negative Trust Anchor
    (NTA), disabling DNSSEC validation for a specific domain; this can be
    used when responses from a domain are known to be failing validation
    due to administrative error rather than because of a spoofing attack.
    Negative trust anchors are strictly temporary; by default they expire
    after one hour, but can be configured to last up to one week.
  * rndc delzone can now be used on zones that were not originally created
    by "rndc addzone".
  * rndc modzone reconfigures a single zone, without requiring the entire
    server to be reconfigured.
  * rndc showzone displays the current configuration of a zone.
  * rndc managed-keys can be used to check the status of RFC 5001 managed
    trust anchors, or to force trust anchors to be refreshed.
  * max-cache-size can now be set to a percentage of available memory. The
    default is 90%.
  * Update forwarding performance has been improved by allowing a single
    TCP connection to be shared by multiple updates.
  * The EDNS Client Subnet (ECS) option is now supported for authoritative
    servers; if a query contains an ECS option then ACLs containing geoip
    or ecs elements can match against the the address encoded in the
    option. This can be used to select a view for a query, so that
    different answers can be provided depending on the client network.
  * The EDNS EXPIRE option has been implemented on the client side,
    allowing a slave server to set the expiration timer correctly when
    transferring zone data from another slave server.
  * The key generation and manipulation tools (dnssec-keygen,
    dnssec-settime, dnssec-importkey, dnssec-keyfromlabel) now take -Psync
    and -Dsync options to set the publication and deletion times of CDS
    and CDNSKEY parent-synchronization records. Both named and
    dnssec-signzone can now publish and remove these records at the
    scheduled times.
  * A new minimal-any option reduces the size of UDP responses for query
    type ANY by returning a single arbitrarily selected RRset instead of
    all RRsets.
  * A new masterfile-style zone option controls the formatting of text
    zone files: When set to full, a zone file is dumped in
    single-line-per-record format.
  * serial-update-method can now be set to date. On update, the serial
    number will be set to the current date in YYYYMMDDNN format.
  * dnssec-signzone -N date sets the serial number to YYYYMMDDNN.
  * named -L <filename> causes named to send log messages to the specified
    file by default instead of to the system log.
  * dig +ttlunits prints TTL values with time-unit suffixes: w, d, h, m, s
    for weeks, days, hours, minutes, and seconds.
  * dig +unknownformat prints dig output in RFC 3597 "unknown record"
    presentation format.
  * dig +ednsopt allows dig to set arbitrary EDNS options on requests.
  * dig +ednsflags allows dig to set yet-to-be-defined EDNS flags on
  * mdig is an alternate version of dig which sends multiple pipelined TCP
    queries to a server. Instead of waiting for a response after sending a
    query, it sends all queries immediately and displays responses in the
    order received.
  * serial-query-rate no longer controls NOTIFY messages. These are
    separately controlled by notify-rate and startup-notify-rate.
  * nsupdate now performs check-names processing by default on records to
    be added. This can be disabled with check-names no.
  * The statistics channel now supports DEFLATE compression, reducing the
    size of the data sent over the network when querying statistics.
  * New counters have been added to the statistics channel to track the
    sizes of incoming queries and outgoing responses in histogram buckets,
    as specified in RSSAC002.
  * A new NXDOMAIN redirect method (option nxdomain-redirect) has been
    added, allowing redirection to a specified DNS namespace instead of a
    single redirect zone.
  * When starting up, named now ensures that no other named process is
    already running.
  * Files created by named to store information, including mkeys and nzf
    files, are now named after their corresponding views unless the view
    name contains characters incompatible with use as a filename. Old
    style filenames (based on the hash of the view name) will still work.

BIND 9.11.1

BIND 9.11.1 is a maintenance release, and addresses the security flaws
disclosed in CVE-2016-6170, CVE-2016-8864, CVE-2016-9131, CVE-2016-9147,
CVE-2016-9444, CVE-2016-9778, CVE-2017-3135, CVE-2017-3136, CVE-2017-3137
and CVE-2017-3138.

BIND 9.11.2

BIND 9.11.2 is a maintenance release, and addresses the security flaws
disclosed in CVE-2017-3140, CVE-2017-3141, CVE-2017-3142 and
CVE-2017-3143. It also addresses several bugs related to the use of an
LMDB database to store data related to zones added via rndc addzone or
catalog zones.

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BIND 9.11.3

BIND 9.11.3 is a maintenance release, and addresses the security flaw
disclosed in CVE-2017-3145.

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BIND 9.11.4

BIND 9.11.4 is a maintenance release, and addresses the security flaw
disclosed in CVE-2018-5738.

BIND 9.11.5

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BIND 9.11.5 is a maintenance release, and also addresses CVE-2018-5741 by
correcting faulty documentation and introducing the following new feature:

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  * 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 9.11.6

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BIND 9.11.6 is a maintenance release, and also addresses the security
flaws disclosed in CVE-2018-5744, CVE-2018-5745, and CVE-2019-6465.

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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 XP, 2003, 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.
               C compiler flags. Defaults to include -g and/or -O2 as
CFLAGS         supported by the compiler. Please include '-g' if you need
               to set CFLAGS.
               System header file directories. Can be used to specify
STD_CINCLUDES  where add-on thread or IPv6 support is, for example.
               Defaults to empty string.
               Any additional preprocessor symbols you want defined.
STD_CDEFINES   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

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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.

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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 https://

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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

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,
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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
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"--with-pkcs11=<PREFIX>", and configure BIND with
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To support the HTTP statistics channel, the server must be linked with at
least one of the following: libxml2 or json-c https:// If these are installed at a nonstandard location,
specify the prefix using --with-libxml2=/prefix or --with-libjson=/prefix.

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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".

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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".

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For DNSTAP packet logging, you must have installed libfstrm https:// and libprotobuf-c https://, and BIND must be configured with

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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.
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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

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.

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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.

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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/
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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.

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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.

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

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
[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
[cleanup]      Minor corrections and refactoring
[doc]          Documentation
[contrib]      Changes to the contributed tools and libraries in the
               'contrib' subdirectory
               Used in the master development branch to reserve change
[placeholder]  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.

ISC's avatar
ISC committed
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  * The original development of BIND 9 was underwritten by the following

    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