If you read the link, you will understand that you can decide for every network interface a personnalize DNS. Not simply a DNS to the whole network, or by machine. Also, 99.99% sure that any modem router box combo can disable the DHCP and act as a bridge.

Note: the question I wrote was a guenuine one, and not sarcasm.

Can't we setup dns adresses in dhcpd? Yes we can! https://manpages.org/dhcpd/8 (After BOOTP support)