syncthing-dns converts DNS queries for <Syncthing ID>.<domain> to lookup
requests to Syncthing's Discovery server. If a match is found, directly
accessible IPv6 addresses are identified and returned.
This is useful as an ad-hoc Dynamic DNS replacement if you are running Syncthing on the target machine anyway.
To set it up you will need to delegate a domain to your machine. By default
it will listen on port 53, alternative you could also instruct a different
DNS server to recurse into syncthing-dns running on a different port.