I just picked up a mini PC (Fujitsu Q5030) and tried to install Linux on it but the CD reader seems not to be reliable. So I used the boot over ethernet function.
As my DHCP server is on the modem of my internet provider, I had to plug directly the computer to my laptop.
EDIT : I did not follow this tutorial but there is better explanation than mine, so I just use this link.
Also I did not have success with the TFTP GUI to manage Mac OS's server so I use the command lines:
sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist sudo launchctl start com.apple.tftpd
You can put your files in
/private/tftpboot/, or modify the directory by editing the file