RFC 2131, "Dynamic Host Configuration Protocol", March 1997Source of RFC: dhc (int)
Errata ID: 5100
Reported By: Fan Wei
Date Reported: 2017-08-29
Section 4.1 says:
Normally, DHCP servers and BOOTP relay agents attempt to deliver DHCPOFFER, DHCPACK and DHCPNAK messages directly to the client using uicast delivery.
It should say:
Normally, DHCP servers and BOOTP relay agents attempt to deliver DHCPOFFER, DHCPACK messages directly to the client using unicast delivery.
According to prior part description in section 4.1: "In all cases, when ’giaddr’ is zero, the server broadcasts any DHCPNAK messages to 0xffffffff.", the DHCP server should not send DHCPNAK in unicast to client unless 'giaddr' is not zero.