Question: In a systemd-based OS, you can change the system hostname by editing /etc/hostname manually and then doing what?

1. Restart dhcpd.
2. Run /etc/hostname.
3. Nothing, the system notices automatically.
4. Notify systemd to update it by restarting the systemd-hostnamed service.

Answer: The correct answer of the above question is Option C:Nothing, the system notices automatically.