Скачать или смотреть DHCP Server for Other Networks (Using DHCP Relay / Helper Address)

🔹 Problem

DHCP uses broadcast messages, and broadcasts do not cross routers.
So when a client in another network sends a DHCP request, the DHCP server cannot hear it directly.

🔹 Solution: DHCP Relay Agent (Helper Address)

How It Works

Client sends a DHCP Discover (broadcast).

The router receives the broadcast.

ip helper-address converts the broadcast into a unicast.

The request is forwarded to the DHCP Server router.

DHCP server replies with IP details.

Router forwards the response back to the client.

Client successfully receives:

IP Address

Subnet Mask

Default Gateway

DNS Server

🔹 Why We Use DHCP Relay

One central DHCP server can serve multiple networks

Reduces configuration overhead

Commonly used in enterprise and ISP networks