zeronsd 0.4 includes a major rewrite of our "authority" code which is the database responsible for holding your records. This includes the fetching code from central as well as the DNS resolution portion of the database.
It also includes a new feature: DNS-over-TLS support. You can enable this by configuring a certificate and key for your server in the configuration file and at the commandline. Please note our sister project zerotier-systemd-manager was also updated to exploit this funcionality; check the README over there for more details.
Updates to logging were also added; we now depend on the tracing crate and now log levels can be configured at the commandline as well as the configuration file. tracing is a much faster logger than the previous implementation, so feel free to dial it up!
Finally, we have upgraded our trust-dns dependency to 0.21.2, which brings in many performance fixes and there were additional fixes to supporting zeronsd in library mode.