The “DORA” protocol in DHCP stands for Discover, Offer, Request, and Acknowledge. It represents the sequence of messages exchanged between a DHCP client and server during the process of obtaining an IP address and network configuration. First, the client sends a Discover message to discover available DHCP servers on the network. The server responds with an Offer message, proposing an IP address and configuration details. The client then sends a Request message to request the offered IP address from a specific DHCP server. Finally, the server acknowledges the request with an Acknowledge message, confirming the lease of the IP address and completing the DHCP configuration process.
DHCP uses the UDP (User Datagram Protocol) as the transport protocol for communication between DHCP clients and servers. UDP is a lightweight, connectionless protocol that allows DHCP messages to be exchanged efficiently over IP networks without the overhead of establishing a persistent connection.
The four steps of DHCP are:
- Discover: The DHCP client broadcasts a discover message to locate available DHCP servers on the network.
- Offer: DHCP servers respond with an offer message, proposing an IP address and network configuration parameters to the client.
- Request: The client selects one of the offered configurations and sends a request message to the chosen DHCP server to lease the offered IP address.
- Acknowledge: The DHCP server acknowledges the client’s request with an acknowledge message, confirming the lease of the IP address and providing final network configuration details.
The lease time in DHCP refers to the duration for which a DHCP client is allowed to use the assigned IP address and network configuration parameters. It is set by the DHCP server when it assigns an IP address to a client. During the lease period, the client can use the IP address and renew its lease before it expires. Lease times can vary depending on network configuration policies and DHCP server settings.
“DORA” in Cisco networking refers to the same DHCP process as described earlier—Discover, Offer, Request, and Acknowledge. Cisco devices and networks implement DHCP using these standard steps to automate IP address assignment and network configuration for devices connecting to the network.