If you have multiple subnets in your network, but you do not have a DHCP server on each subnet and your routers cannot relay ...

If you have multiple subnets in your network, but you do not have a DHCP server on each subnet and your routers cannot relay DHCP/BOOTP messages, you might want to configure relay agents. A DHCP/BOOTP relay agent forwards DHCP and BOOTP message traffic between the DHCP-enabled clients on the local subnet and a remote DHCP server located on another subnet by using the IP address of the remote DHCP server.