When a client is requesting an initial address lease from a DHCP server, why is the DHCPREQUEST message sent as a broadcast?

Question:
When a client is requesting an initial address lease from a DHCP server, why is the DHCPREQUEST message sent as a broadcast?

• The client does not yet know the IP address of the DHCP server that sent the offer.
• The DHCP server may be on a different subnet, so the request must be sent as a broadcast.
• The client does not have a MAC address assigned yet, so it cannot send a unicast message at Layer 2.
• The client may have received offers from multiple servers, and the broadcast serves to implicitly decline those other offers.

Explanation: During the initial DHCP exchange between a client and server, the client broadcasts a DHCPDISCOVER message looking for DHCP servers. Multiple servers may be configured to respond to this request with DHCPOFFER messages. The client will choose the lease from one of the servers by sending a DHCPREQUEST message. It sends this message as a broadcast so that the other DHCP servers that sent offers will know that their offers were declined and the corresponding address can go back into the pool.

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