Official systemd homepage[1] begs to differ, it says systemd is an init system including many features among which is name resolution:
>systemd (...) provides a system and service manager that runs as PID 1 and starts the rest of the system. (...) Other parts include a logging daemon, (...), log forwarding, and name resolution.
[1]: https://freedesktop.org/wiki/Software/systemd/
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Not sure where it is a separate package, just checked debian and arch, the systemd package contains systemd-resolved.
https://packages.debian.org/jessie/amd64/systemd/filelist
https://www.archlinux.org/packages/core/x86_64/systemd/