For the situations where there is more than one LAN, each with its own subnet number, there are two ways. First of all, you can set up a seperate server oneach subnet. Secondly, a feature of some routers known as "BOOTP forwarding"to forward DHCP or BOOTP requests to a server on another subnet and toforward the REPLIES back to the client.
The part of such a router (or server actingas a router) that does this is called a "BOOTP forwarding agent". Typically youhave to enable it on the interface to the subnet to be SERVED and have toconfigure it with the IP ADDRESS of the DHCP or BOOTP server. On a Cisco router,the address is known as the "UDP Helper Address". 

For the situations where there is more than one LAN, each with its own subnet number, there are two ways. First of all, you can set up a seperate server oneach subnet. Secondly, a feature of some routers known as "BOOTP forwarding"to forward DHCP or BOOTP requests to a server on another subnet and toforward the replies back to the client.
The part of such a router (or server actingas a router) that does this is called a "BOOTP forwarding agent". Typically youhave to enable it on the interface to the subnet to be served and have toconfigure it with the IP address of the DHCP or BOOTP server. On a Cisco router,the address is known as the "UDP Helper Address".