Knot DNS is an open-source authoritative-only server for the Domain Name System. It was created from scratch and is actively developed by CZ.NIC, the .CZ domain registry. The purpose of this project is to supply an alternative open-source implementation of an authoritative DNS server suitable for TLD operators to increase overall security, stability and resiliency of the Domain Name System. It is implemented as a multi-threaded daemon, using a number of programming techniques and data structures to make the server very fast, notably Read-copy-update or a special kind of a radix tree.

Knot DNS uses a zone parser written in Ragel to achieve very fast loading of the zones at the startup. It is also able to add and remove zones on the fly by changing the configuration file and reloading the server using the 'knotc' utility.

Since version 3.0.0, Knot DNS supports a high performance XDP mode in Linux, which can improve response performance significantly.

Apart from Knot DNS, there is also it's sibling software Knot Resolver, which is a recursive DNS resolver.

New in 1.2.0: Response Rate Limiting, Dynamic DNS, and a new remote control utility.

New in 1.3.0: new zone parser in Ragel (replaces zone compilation) and several client utilities (kdig, khost and knsupdate).

New in 1.4.0: automatic DNSSEC signing of the managed zones.

New in 1.5.0: query modules with two new modules: "Automatic forward/reverse records" and dnstap.