DHCP DORA process — why 4 steps instead of 2?
itayitayy · posted · 71 views
If the client just needs an IP from the server, why can't it be a simple request-response? Why does DHCP need Discover, Offer, Request, AND Acknowledge? Seems overcomplicated. What happens if there are multiple DHCP servers? Does the client pick one?
- The Discover is a broadcast because the client doesn't know any DHCP server exists. The Offer is the server saying "here's an IP for you." The Request is ALSO a broadcast — this is the key part — so that ALL DHCP servers on the network hear it and know which server was chosen. The ones not chosen can reclaim their offered IP. The Ack confirms the lease. — 22maya2n2,
- Try running DHCP in the lab here and watch the capture tab. You'll see all 4 packets with source/destination MACs and IPs. The Discover goes to 255.255.255.255 from 0.0.0.0. Seeing it happen packet by packet makes the whole process click. — NivSa,
- The broadcast Request part is what I was missing. It's not just telling the chosen server "yes please" — it's telling ALL servers on the network so the losers can take back their offers. That actually makes the 4-step design make sense now. — itayitayy,
- Good idea, I just ran it in the lab with capture on. Seeing the 0.0.0.0 source and ff:ff:ff:ff:ff:ff destination on the Discover made it real. The capture tab here is honestly underrated for learning protocols. — itayitayy,
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