DHCP Server and Clients Communication

1. The DHCP client broadcasts a DHCP discover message to the local subnet.
2. A DHCP server can respond with a DHCP offer message (DHCPOFFER) that contains an offered IP address for lease to the client.
3. If no DHCP servers respond to the client discovery request, the client can proceed in either of two ways:
   • If the client is running under Windows 2000 and IP auto-configuration has not been disabled, the client self-configures an IP address for use with automatic client configuration.
   • If the client is not running under Windows 2000 (or IP auto-configuration has been disabled), the client fails to initialize. Instead, if left running, it continues to resend DHCP discover messages in the background (four times every five minutes) until it receives a DHCP offer message from a server.
4. As soon as a DHCP offer message is received, the client selects the offered address by replying to the server with a DHCP request.
5. Typically, the offering server sends a DHCP acknowledgement message (DHCPACK) , approving the lease.
   Also, other DHCP options information is included in the acknowledgement.
6. Once the client receives acknowledgment, it configures its TCP/IP properties using the information in the reply and joins the network.