DHCP Broadcasts, How Routers/DHCP Relay Agents Handle Them
Tuesday, August 24th, 20102010-08-24 Initial Post
I've always wondered how a DHCP server is able to communicate with clients on different subnets if both the client and server use broadcasts. Basically, the router (or DHCP relay agent, that's on the client's subnet) intercepts the DHCP broadcasts sent from the client. The router knows that the broadcast is DHCP-related because the destination port is UDP 67, which what the DHCP service listens on.
The router takes the broadcast and "repackages" it as a unicast message to the DHCP server. That part is easy to understand. (more…)
