DHCPOFFER is the DHCP server’s response to a client’s DHCPDISCOVER. It proposes an IP address and other configuration parameters as the second step of the four-message DORA exchange. section 4.1.1 section 4.4
Recognize the operational behavior of an OFFER:
- Returns an offered IP address and other client configuration from the DHCP server. section 4.4
- Uses UDP, with DHCP servers sourcing messages from and listening on port 67; clients use port 68. section 4.1.1
- Addresses the offer either to the offered IP address by unicast or to 255.255.255.255 by broadcast. section 4.4
- Precedes DHCPREQUEST, through which the client accepts an offer; the server then confirms it with DHCPACK. section 4.1.1 section 4.4
DORA exchange
A client broadcasts DHCPDISCOVER to locate DHCP servers. A server replies with DHCPOFFER, the client broadcasts DHCPREQUEST to accept an offer, and the server sends DHCPACK to finalize the lease. If multiple servers respond, the client typically accepts the first offer. section 4.4
Figure 4.2 Leasing an IPv4 address via DHCP (the DORA process): (1) DISCOVER from client to server, (2) OFFER from server to client, (3) REQUEST from client to server, (4) ACK from server to client.
Trace the four-message IPv4 DHCP exchange and locate DHCPOFFER between DHCPDISCOVER and DHCPREQUEST. section 4.1.1
