Unbound is a validating, recursive, and caching DNS resolver software product from NLnet Labs. It is distributed free of charge in open-source form under the Modified BSD License.
Features Caching resolver with prefetching of popular items before they expire DNS over TLS forwarding and server, with domain-validation DNS over HTTPS DNS over QUIC Query name minimization Aggressive use of DNSSEC-Validated Cache Authority zones, for a local copy of the root zone DNS64 DNSCrypt Domain Name System Security Extensions (DNSSEC) validating EDNS client subnet
History Originally designed by Jakob Schlyter of Kirei and Roy Arends of Nominet in 2004, funding was provided by VeriSign and ep.net to develop a prototype written in Java (David Blacka and Matt Larson, VeriSign). In 2006, the prototype was re-written for high-performance in the C programming language by NLnet Labs.
Unbound is designed as a set of modular components that incorporate modern features, such as enhanced security (DNSSEC) validation, Internet Protocol Version 6 (IPv6), and a client resolver application programming interface library as an integral part of the architecture. Originally written for POSIX-compatible Unix-like operating system, it runs on FreeBSD, OpenBSD, NetBSD, macOS, and Linux, as well as Microsoft Windows.
Reception Unbound has supplanted the Berkeley Internet Name Daemon (BIND) as the default, base-system name server in FreeBSD and OpenBSD, where it is perceived as smaller, more modern, and more secure for most applications.
See also NSD, an authoritative name server, also from NLnet Labs Comparison of DNS server software
References
External links
Running Unbound in a Docker Container Unbound DNS Tutorial with examples and explanations