DHCP Server Deployment Across Subnets and NAT Routers

In network design, a DHCP (Dynamic Host Configuration Protocol) server is usually located on the same subnet or network segment as the DHCP client to efficiently assign IP addresses. When a DHCP server needs to provide addresses to clients on a different subnet, a DHCP relay is used. The local gateway typically acts as the DHCP relay agent by utilizing an IP helper address.

Deploying a DHCP server across a Network Address Translation (NAT) router is generally not recommended. NAT routers designate the boundary of a particular network, meaning services like DHCP should remain within the same administrative domain as their clients. It is uncommon to have a DHCP server outside the network distributing IP addresses to internal hosts, since this configuration can introduce unnecessary complexity and potential issues, such as UDP port management. Therefore, DHCP servers are typically kept on the same network segment to avoid these complications.