Sent by the client as the first step of the DHCP client/server interaction. The purpose of the DHCPDISCOVER is for the client to "discover" what servers are out there and what network parameters they have to offer.

DHCPOFFER

Sent by the server to the client in response to a DHCPDISCOVER. The server uses the DHCPOFFER message to "offer" an IP address, lease time, and network configuration parameters to the client.

DHCPREQUEST

Sent by the client to the server in response to a DHCPOFFER. The "server identifier" field of the DHCPREQUEST indicates which server the client has chosen to further interact with. All servers that sent the client a DHCPOFFER receive the DHCPREQUEST. The ones that are not chosen simply use the message as notification that they have not been chosen. The server that is chosen responds to the request, either with a DHCPACK or a DHCPNAK.

DHCPACK

Sent by the server to the client in response to a DHCPREQUEST. The DHCPACK indicates that the server "acknowledges" the request, and the DHCPACK message contains fields which indicate the IP address, lease time, and network configuration parameters that the client is being configured with.

DHCPNAK

Sent by the server to the client in response to a DHCPREQUEST. The DHCPNAK indicates that the server does not acknowledge the request, and does not agree to lease the specified IP address.

DHCPRELEASE

Sent by the client to the server to give up an IP address lease. If the client knows that it no longer needs an IP address, it should send the server a DHCPRELEASE.

DHCPDECLINE

Sent by the client to the server in response to a DHCPACK. If the client receives a DHCPACK, but, for some reason, is not satisfied with the lease time and/or network parameters in the message, it can send the server a DHCPDECLINE indicating that it refuses to use the IP address.

Left DHCP Server

DHCP Client/Server Interaction