Unbound is free and open-source DNS server software that can be used for validating, recursive, and caching DNS resolvers. It’s a feature-rich DNS server that supports DNS-over-TLS (DoT), DNS-over-HTTPS (DoH), Query Name Minimisation, the Aggressive Use of DNSSEC-Validated Cache, and support for authority zones. Unbound is focused on the privacy and security of DNS, but without sacrificing the speed and performance.

Source: How to Set Up Local DNS Resolver with Unbound on Ubuntu 22.04 – Howtoforge