I've done something along these lines with a very simple DNS and DHCP server implementation as an Arduino library: https://github.com/pkulchenko/DHCPLite/ https

I've done something along these lines with a very simple DNS and DHCP server implementation as an Arduino library: https://github.com/pkulchenko/DHCPLite/ https://github.com/pkulchenko/DHCPLite/. It is fairly short and while I don't claim it being fully correct, it was tested with different clients successfully; it was great learning experience.