Mac hardware blocking on dhcp server

I have a rhel 6.10 dhcp server. I have a need to block 1 certain mac address on it. The nature of this server is that all connections to it are initially "unknown", so I can't really set up a range to allow only known mac addresses. It is used a dormitory style scenario, so there are lots of devices connecting to it. I'd rather avoid some sort of software method.

Is there a way to modify the /etc/dhcp/dhcpd.conf or the /var/lib/dhcp/dhcpd.lease file? I need to block 1 mac address from being able to obtain an IP.