Knot DNS 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 four of those built-in - iterator, validator and two caching modules. 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.
Several cache backends (LMDB, Redis and Memcached), 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.
Knot Resolver is packaged for Debian, Fedora, Ubuntu, Homebrew and NixOS/Nixpkgs. You can also find it as the default DNS resolver in our open-source router Turris Omnia. See the Knot-resolver homepage for more information.
Knot DNS 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 -it cznic/knot-resolver
See the build page hub.docker.com/r/cznic/knot-resolver for more information and options.
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.
