IETF RFC 2563 PDF

Operating Systems are now attempting to support ad-hoc networks of two or more systems, while keeping user configuration at a minimum. To accommodate this, in the absence of a central configuration mechanism (DHCP), some OS's are automatically choosing a link-local IP address which will allow them to communicate only with other hosts on the same link. This address will not allow the OS to communicate with anything beyond a router. However, some sites depend on the fact that a host with no DHCP response will have no IP address. This document describes a mechanism by which DHCP servers are able to tell clients that they do not have an IP address to offer, and that the client should not generate an IP address it's own.