2. Server response: DHCP OFFER

Because the central DHCP service is provided by two DHCP servers, normally a client will receive two offers of an IP address in response to its initial DISCOVER request. There are exceptions if one server is down, or has no free addresses available.

Because the DHCP servers see the request as originating from the router address, they will return it to the router interface on the subnet in question. The router is responsible for forwarding the responses to the client. For a client on the subnet, the reponses will be along the following lines:

   UDP (00:D0:BC:00:11:22) > (00:00:39:1C:0C:32) DHCP OFFER
   UDP (00:D0:BC:00:11:22) > (00:00:39:1C:0C:32) DHCP OFFER

Note that the destination IP address is that which the server is offering to the client while the destination MAC address is that of the client's network interface. Thus the packet will reach the client even though it does not yet have its IP address.

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