systemd has a few services that are mostly just about providing a common interface to information about the current machine, or other machines.

Daemons for recording information

There's hostnamed(8), localed(8) and timedated(8) for providing a wirtable D-Bus interface to the system's hostname, locale and time respectively; and machined(8), which provides information about the "chassis type" or "form factor".

It may sound wasteful to have an entire server just to make this information available over D-Bus, but when a server is waiting for requests it is often paged-out, meaning it's only consuming a small amount of memory.

However, this wasn't good enough for the systemd developers, so these services are D-Bus activated, which means that they'll only be started when something makes a request of them. Combined with the fact that these services will exit when idle, and they don't even need to consume that small amount of memory any more.

One user of hostnamed(8) is the myhostname NSS module, which if nsswitch.conf is configured correctly, allows the addresses of the curent machine to be resolved without hard-coding them in the hosts file.

machined supporting containers

machined(8) also manages information about other machines, though this stretches the definition of "machine" a little, since it means the host machine, containers and virtual machines, rather than multiple physical machines on a network.

machined(8) is usually used indiectly by your virtual-machine manager or container manager, to provide a common interface for managing them with machinectl(1).

The usual management tasks aren't much more than just seeing which machines are online and stopping them if necessary, but if a machine is registered with machined(8), then other systemd management commands, such as systemctl(1) allow you to pass a machine name to the --machine option, to get it to operate on that machine instead of the host.

systemd comes with a container manager built-in, called systemd-nspawn(1), which has more full integration with machinectl(1), allowing the download of container images, configuring whether they start on-boot, and commands to log-in to the container and copy files in or out.