Those options were also added with systemd 256, but sadly were missed out in #307068. These options are documented in: - [systemd 256 changelog](https://github.com/systemd/systemd/releases/tag/v256) (search for `UseDomains=`) - [networkd.conf(5)](https://www.freedesktop.org/software/systemd/man/256/networkd.conf.html#UseDomains=) - [systemd.network(5)](https://www.freedesktop.org/software/systemd/man/256/systemd.network.html#UseDomains=)