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## Supported platforms

In general, this version of BIND will build and run on any POSIX-compliant
system with a C11-compliant C compiler, BSD-style sockets with RFC-compliant
IPv6 support, and POSIX-compliant threads, plus the following mandatory
libraries:

- `libuv` for asynchronous I/O operations and event loops
- `libssl` and `libcrypto` from OpenSSL for cryptography

Use of the following libraries is optional:

- `libjemalloc` for improved memory allocation performance
- `libnghttp2` for DNS-over-HTTPS (DoH) support

The following C11 features are used in BIND 9:

* Atomic operations support, either in the form of C11 atomics or
  `__atomic` builtin operations.

* Thread Local Storage support, either in the form of C11
  `_Thread_local`/`thread_local`, or the `__thread` GCC extension.

The C11 variants are preferred.

BIND 9.17 requires a fairly recent version of `libuv` (at least 1.x).  For
some of the older systems listed below, you will have to install an updated
`libuv` package from sources such as EPEL, PPA, or other native sources for
updated packages. The other option is to build and install `libuv` from
source.

Certain optional BIND features have additional library dependencies.
These include:

* `libfstrm` and `libprotobuf-c` for DNSTAP
* `libidn2` for display of internationalized domain names in `dig`
* `libjson-c` for JSON statistics
* `libmaxminddb` for geolocation
* `libnghttp2` for DNS over HTTPS
* `libxml2` for XML statistics
* `libz` for compression of the HTTP statistics channel
* `readline` for line editing in `nsupdate` and `nslookup`

ISC regularly tests BIND on many operating systems and architectures, but
lacks the resources to test all of them. Consequently, ISC is only able to
offer support on a "best effort" basis for some.

### Regularly tested platforms

As of Dec 2021, BIND 9.17 is fully supported and regularly tested on the
following systems:

* Debian 9, 10, 11
* Ubuntu LTS 18.04, 20.04
* Fedora 35
* Red Hat Enterprise Linux / CentOS / Oracle Linux 7, 8
* FreeBSD 12.3, 13.0
* OpenBSD 7.0
* Alpine Linux 3.15

The amd64, i386, armhf and arm64 CPU architectures are all fully supported.

### Best effort

The following are platforms on which BIND is known to build and run.
ISC makes every effort to fix bugs on these platforms, but may be unable
to do so quickly due to lack of hardware, less familiarity on the part
of engineering staff, and other constraints. None of these are tested
regularly by ISC.

* macOS 10.12+
* Solaris 11
* NetBSD
* Other Linux distributions still supported by their vendors, such as:
    * Ubuntu 20.10+
    * Gentoo
    * Arch Linux
* OpenWRT/LEDE 17.01+
* Other CPU architectures (mips, mipsel, sparc, ...)

### Community maintained

These systems may not all have the required dependencies for building BIND
easily available, although it will be possible in many cases to compile
those directly from source. The community and interested parties may wish
to help with maintenance, and we welcome patch contributions, although we
cannot guarantee that we will accept them.  All contributions will be
assessed against the risk of adverse effect on officially supported
platforms.

* Platforms past or close to their respective EOL dates, such as:
    * Ubuntu 14.04, 16.04 (Ubuntu ESM releases are not supported)
    * CentOS 6
    * Debian Jessie
    * FreeBSD 10.x, 11.x

## Unsupported platforms

These are platforms on which BIND 9.17 is known *not* to build or run:

* Platforms without at least OpenSSL 1.0.2
* Windows
* Solaris 10 and older
* Platforms that don't support IPv6 Advanced Socket API (RFC 3542)
* Platforms that don't support atomic operations (via compiler or library)
* Linux without NPTL (Native POSIX Thread Library)
* Platforms on which `libuv` cannot be compiled