Knot Resolver is a caching full resolver implementation written in C and LuaJIT, both a resolver library and a daemon. The core architecture is tiny and efficient, and provides a foundation and a state-machine like API for extensions. There are three modules built-in - iterator, validator, cache, and a few more are loaded by default. Most of the rich features are written in Lua(JIT) and C. Batteries are included, but optional.

The LuaJIT modules, support DNS privacy and DNSSEC, and persistent cache with low memory footprint make it a great personal DNS resolver or a research tool to tap into DNS data. TL;DR it's the OpenResty of DNS.

Strong filtering rules, and auto-configuration with etcd make it a great large-scale resolver solution.

The server adopts a different scaling strategy than the rest of the DNS recursors - no threading, shared-nothing architecture (except MVCC cache that may be shared) that allows you to pin instances on available CPU cores and grow by self-replication. You can start and stop additional nodes depending on the contention without downtime.

It also has strong support for DNS over TCP, notably TCP Fast-Open, query pipelining and deduplication, and response reordering.

The latest stable packages for various distributions are available in our upstream repository. Follow the installation instructions to add this repository to your system.

Knot Resolver is also available from the following distributions' repositories.

• Fedora and Fedora EPEL
• Debian stable, Debian testing, Debian unstable
• Ubuntu
• Arch Linux
• Alpine Linux

Knot Resolver mainly depends on Knot DNS libraries, LuaJIT and libuv. See the Building project documentation page for more information.

This is simple and doesn't require any dependencies or system modifications, just run:

$ docker run -Pit cznic/knot-resolver

The images are meant as an easy way to try knot-resolver, and they're not designed for production use.

The project builds a resolver library in the lib directory, and a daemon in the daemon directory. It requires no configuration or parameters to run a server on localhost.

$ kresd

See the documentation at knot-resolver.readthedocs.io for more options.

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