The four steps of DHCP (Dynamic Host Configuration Protocol) involve the process of a client obtaining an IP address and other network configuration information from a DHCP server:
- Discover: In the Discover step, the client broadcasts a DHCP Discover message to find available DHCP servers on the network. This broadcast message is sent to the local subnet and includes the client’s hardware address (MAC address).
- Offer: When a DHCP server receives a Discover message, it responds with a DHCP Offer message. This message includes an IP address lease offer for the client, along with other configuration parameters such as subnet mask, default gateway, DNS server addresses, and lease duration. The Offer message is unicast to the client.
- Request: Upon receiving one or more Offer messages, the client selects one DHCP server and broadcasts a DHCP Request message. This message confirms the acceptance of the offered IP address lease from the chosen DHCP server.
- Acknowledge: The DHCP server that receives the Request message sends a DHCP Acknowledge (Ack) message to the client. This message includes the final configuration details and confirms that the IP address lease has been granted to the client. The Ack message is unicast to the client, completing the DHCP process.
The four types of DHCP packets refer to the different message types exchanged between DHCP clients and servers during the DHCP process:
- DHCP Discover: Sent by a DHCP client to discover available DHCP servers on the network. This broadcast message includes the client’s MAC address.
- DHCP Offer: Sent by a DHCP server in response to a DHCP Discover message from a client. It offers an IP address lease and other configuration parameters to the client.
- DHCP Request: Sent by a DHCP client to request an IP address lease from a specific DHCP server. This message acknowledges the DHCP Offer from the selected server.
- DHCP Acknowledge (Ack): Sent by the DHCP server to the client in response to a DHCP Request message. It confirms that the IP address lease has been granted to the client, along with the final configuration details.
These DHCP packets facilitate the negotiation and allocation of IP addresses and network configuration settings between DHCP clients and servers.
The four steps of DHCP operation outline the sequence of actions taken by DHCP clients and servers to allocate and manage IP addresses dynamically:
- Initialization: The client initializes its network interface and sends a DHCP Discover message to locate available DHCP servers on the network.
- Lease Offer: DHCP servers respond with DHCP Offer messages containing IP address lease offers and other configuration parameters. The client selects one offer and sends a DHCP Request message to the chosen server.
- Request and Acknowledge: The DHCP server acknowledges the client’s request by sending a DHCP Acknowledge (Ack) message, confirming the IP address lease assignment and providing final configuration details.
- Lease Renewal: Throughout the lease period, the client may renew the IP address lease by sending a DHCP Request message to the original DHCP server. The server responds with a DHCP Acknowledge message to renew the lease. If the client moves to a new network, it repeats the DHCP Discover process to obtain a new lease from a DHCP server on the new network.
These steps ensure efficient IP address allocation and management within DHCP-enabled networks, supporting seamless connectivity for devices and users.