08/08/2025
Let’s Know about DHCP servers DORA process. ..
The DORA process is the four-step sequence DHCP uses to dynamically assign IP addresses to devices on a network. DORA stands for:
D discover → O offer → R request → A acknowledgment
Here’s a breakdown of each steps
#1. Discover (Client → Server):
A device joining the network broadcasts a DHCP Discover message (to `255.255.255.255` or `ff02::1:2` in IPv6).
-Purpose: "I’m new here! Are there any DHCP servers?"
- **Technical details**:
- Sent as a UDP broadcast (port 67).
- Contains the device’s MAC address.
2. Offer (Server → Client):
DHCP servers respond with a **DHCP Offer** message.
Purpose: "I’m a DHCP server! Here’s an IP address you can use."
Technical details:
- The server reserves an IP from its pool and proposes it to the client.
- Includes subnet mask, gateway, DNS servers, and lease time.
- Also sent as a broadcast (since the client lacks an IP).
3. Request (Client → Server):
The client broadcasts a DHCP Request message.
Purpose: "I accept your offer! Please assign me this IP."
Why broadcast?:
Informs all DHCP servers which offer was accepted (and tells others to withdraw their offers).
- Prevents multiple servers from assigning the same IP.
4. Acknowledgment (Server → Client):
The chosen server sends a DHCP ACK(Acknowledgment).
Purpose: "Confirmed! The IP is yours. Here’s your full config."
Result:
- The client applies the IP/networking settings.
- The IP is marked as "leased" in the server’s pool.
-If failure:
- If the server sends DHCP NAK (Negative ACK), the client restarts DORA.
