Question 356

Broadcast The Rejection

Two DHCP servers on one segment both answer a client's DHCPDISCOVER with a DHCPOFFER. The client accepts the offer from server B.

Its DHCPREQUEST is broadcast, not unicast to B. Why?

A

Because DHCPREQUEST carries no server identifier, so servers must infer from the transaction id whether their offer was accepted.

B

So the client can time which server replies first and switch to that one if B is slow.

C

So server A sees the message, learns its offer was refused, and can return the reserved address to its pool. The chosen server is named in the server identifier option.

D

Because DHCP has no unicast mode: every DHCP message in every state goes to 255.255.255.255.