DHCPMessageType

DHCPMessageType is the DHCP option used to indicate the type of a DHCP message. It is defined as option 53 in the DHCP protocol and is encoded as a single byte within a DHCP message. The value maps to specific message types that drive the DHCP negotiation between clients and servers.

The most commonly supported values are 1 through 8, corresponding to: 1 = DHCPDISCOVER, 2 = DHCPOFFER, 3 = DHCPREQUEST, 4 = DHCPDECLINE, 5 = DHCPACK, 6 = DHCPNAK, 7 = DHCPRELEASE, and 8 = DHCPINFORM. These types represent the stages of the DHCP exchange, from discovery to offer, request and acknowledgment, negative acknowledgment, release of a lease, or an information-only request. In practice, a client begins with DHCPDISCOVER, a server responds with DHCPOFFER, the client sends DHCPREQUEST, and the server replies with DHCPACK or DHCPNAK. DHCPINFORM is used by clients that already have an IP address and seek additional configuration data.

Usage and interpretation are standardized in the DHCP specifications, notably RFC 2131 (Dynamic Host Configuration Protocol) and RFC 2132 (DHCP Options). Implementations may expose DHCPMessageType as a typed enum or constant set in software libraries to aid parsing and handling. While the standard defines eight primary message types, extensions or vendor-specific implementations may introduce additional message types in certain contexts.

See also: Dynamic Host Configuration Protocol, DHCP options, RFC 2131, RFC 2132.