Unbound (DNS server) explained

Unbound
Developer:	NLnet Labs
Latest Release Version:
Programming Language:	C
Operating System:	Unix-like, Windows
Genre:	DNS server
License:	BSD license

Unbound is a validating, recursive, and caching DNS resolver product from NLnet Labs. It is distributed free of charge in open-source form under the BSD license.

Features

• Caching resolver with prefetching of popular items before they expire
• DNS over TLS forwarding and server, with domain-validation^[1]
• DNS over HTTPS^{[2] [3]}
• Query Name Minimization^[4]
• Aggressive Use of DNSSEC-Validated Cache^[5]
• Authority zones, for a local copy of the root zone^[6]
• DNS64
• DNSCrypt^[7]
• 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.^[8]

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.^{[9] [10]}

See also

• NSD, an authoritative name server, also from NLnet Labs
• Comparison of DNS server software

External links

• • Running Unbound in a Docker Container
• Unbound DNS Tutorial with examples and explanations

Notes and References

1. Web site: Actually secure DNS over TLS in Unbound. 2018-06-07. 2018-06-11. Ctrl blog.
2. Web site: Wijngaards . Wouter. Unbound 1.12.0 released . NLnet Labs . 8 October 2020 . 26 October 2020 .
3. Web site: Dolmans . Ralph . DNS-over-HTTPS in Unbound . The NLnet Labs Blog . 9 October 2020 . 26 October 2020 .
4. Web site: Wijngaards . Wouter . Unbound 1.5.7 release . unbound-users (Mailing List) . 10 December 2015 . 26 October 2020 .
5. Web site: Wijngaards . Wouter . Unbound 1.7.0 Release . unbound-users (Mailing List) . 15 March 2018 . 26 October 2020 .
6. Web site: Wijngaards . Wouter . Unbound 1.7.0 Release . unbound-users (Mailing List) . 15 March 2018 . 26 October 2020 .
7. Web site: unbound.conf(5) - Unbound 1.19.0 Documentation. NLnet Labs. 8 November 2023. 2 February 2024.
8. Web site: Open source DNS server takes on BIND. Eric Brown. 2020-03-21.
9. Web site: Heads Up: BIND Disabled in Base. OpenBSD Journal. August 23, 2014. June 10, 2015.
10. Web site: DNS in FreeBSD 10. September 24, 2014 . Dag-Erling Smørgrav. Dag-Erling Smørgrav's blog. June 10, 2015.