RFC 1541 (rfc1541) - Page 2 of 39

Dynamic Host Configuration Protocol

RFC 1541          Dynamic Host Configuration Protocol       October 1993


   4.1 Constructing and sending DHCP messages. . . . . . . . . . . . 21
   4.2 DHCP server administrative controls . . . . . . . . . . . . . 23
   4.3 DHCP server behavior. . . . . . . . . . . . . . . . . . . . . 24
   4.3.1 DHCPDISCOVER message. . . . . . . . . . . . . . . . . . . . 24
   4.3.2 DHCPREQUEST message . . . . . . . . . . . . . . . . . . . . 27
   4.3.3 DHCPDECLINE message . . . . . . . . . . . . . . . . . . . . 29
   4.3.4 DHCPRELEASE message . . . . . . . . . . . . . . . . . . . . 29
   4.4 DHCP client behavior. . . . . . . . . . . . . . . . . . . . . 29
   4.4.1 Initialization and allocation of network address. . . . . . 29
   4.4.2 Initialization with known network address . . . . . . . . . 33
   4.4.3 Initialization with a known DHCP server address . . . . . . 34
   4.4.4 Reacquisition and expiration. . . . . . . . . . . . . . . . 34
   4.4.5 DHCPRELEASE . . . . . . . . . . . . . . . . . . . . . . . . 35
   5. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 35
   6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36
   7. Security Considerations. . . . . . . . . . . . . . . . . . . . 37
   8. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 38
   A. Host Configuration Parameters  . . . . . . . . . . . . . . . . 39

List of Figures

   1. Format of a DHCP message . . . . . . . . . . . . . . . . . . .  9
   2. Format of the 'flags' field. . . . . . . . . . . . . . . . . . 10
   3. Timeline diagram of messages exchanged between DHCP client and
      servers when allocating a new network address. . . . . . . . . 15
   4. Timeline diagram of messages exchanged between DHCP client and
      servers when reusing a previously allocated network address. . 18
   5. State-transition diagram for DHCP clients. . . . . . . . . . . 31

List of Tables

   1. Description of fields in a DHCP message. . . . . . . . . . . . 14
   2. DHCP messages. . . . . . . . . . . . . . . . . . . . . . . . . 16
   3. Fields and options used by DHCP servers. . . . . . . . . . . . 25
   4. Fields and options used by DHCP clients. . . . . . . . . . . . 32

1. Introduction

   The Dynamic Host Configuration Protocol (DHCP) provides configuration
   parameters to Internet hosts.  DHCP consists of two components: a
   protocol for delivering host-specific configuration parameters from a
   DHCP server to a host and a mechanism for allocation of network
   addresses to hosts.

   DHCP is built on a client-server model, where designated DHCP server
   hosts allocate network addresses and deliver configuration parameters
   to dynamically configured hosts.  Throughout the remainder of this
   document, the term "server" refers to a host providing initialization



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