APPLICATION LAYER
INTRODUCTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The client does not yet know the IP address of the DHCP server that sent the offer.
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The client may have received offers from multiple servers, and the broadcast serves to implicitly decline those other offers.
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The DHCP server may be on a different subnet, so the request must be sent as a broadcast.
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The client does not have a MAC address assigned yet, so it cannot send a unicast message at Layer 2.
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Detailed explanation-1: -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.
Detailed explanation-2: -First, the client sends out a DHCPDISCOVER message requesting an IP address. The DHCPDISCOVER message contains an identifier unique to the client (typically the MAC address).
Detailed explanation-3: -Explanation. Assuming all went well with the DHCP discovery process, the correct sequence of DHCP messages exchanged between the server and client is: DHCPDISCOVER-> DHCPOFFER-> DHCPREQUEST-> DHCPACK. A client sends a DHCPDISCOVER message with a source address of 0.0.
Detailed explanation-4: -255.255. When a DHCP client needs to send a DHCP Discover packet in order to seek DHCP servers, the client will use this IP address of 255.255. 255.255 as the destination in the IP header because it has no knowledge of the IP addresses of DHCP servers.