A DHCP server that receives a DHCPDISCOVER message may respond with a DHCPOFFER message on UDP port 68 (BootP client). ... In the event that the DHCP server is not on the local subnet, the DHCP server will send the DHCPOFFER, as a unicast packet, on UDP port 67, back to the DHCP/BootP Relay Agent from which the DHCPDISCOVER came. Reference: https://www.cisco.com/c/en/us/support/docs/ip/dynamic-address-allocation- resolution/27470-100.html