This document updates the DHCP protocol specification that appears in RFC1541. A new DHCP message type, DHCPINFORM, has been added; see section 3.4, 4.3 and 4.4 for details. The classing mechanism for identifying DHCP clients to DHCP servers has been extended to include "vendor" classes as defined in sections 4.2 and 4.3. The minimum lease time restriction has been removed. Finally, many editorial changes have been made to clarify the text as a result of experience gained in DHCP interoperability tests.