DHCP Dora process

DORA in simple words is the process through which a DHCP client acquires an IP address from a DHCP server in the network

D- Discover: When a machine boots up in lan and it doesnt have an IP address configured , it would send a DHCP discover broadcast to the network. It will have a destination IP of 25.255.255.255. It also includes it mac address encapsculated in the package. The layer 2 destination would be ff:ff:ff:ff:ff:ff, ie to add devices in the network. The switch port which received the package would then forward it to all other ports in the switch except on the one from which the request is received.

O- Offer: If there is a dhcp server listening on the network, it will respond back to the DHCPrequest package with an offer package. The offer package is again a broadcast to 255.255.255.255, but it will have the destination mac address set to the DHCP client's mac address. The source mac address will be that of the DHCP server. The offer package will contain the IP address,DNS,gateway etc as well

R- Request: The dhcp client will get similar offers from all dhcp servers in the network and it will typically accept the first one that it receives.It will then send a request to the DHCP for the offered IP address.

A-Acknowledge: When DHCP received the DHCp Request from the client for the IP address, it will send back a DHCP aknowledge, thereby allocating that IP address to the client

Comments

  1. The DORA process are a part of the client message from the DHCP protocol perspective.In which only clients that are willing to request an IP address send these messages.

    Thanks
    Silvester Norman

    Change MAC Address

    ReplyDelete
    Replies
    1. You are right Silvester. Only if the client is configured to obtain IP address automatically(that is, from DHCP), this process will be initiated

      Delete
  2. Is the above information correct about the Dora process ?

    ReplyDelete

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