Re: question about dhcp & secondary IP address

["Michael J. Lewis" <[e-mail]>]

> We use Windows NT 3.51 sever as DHCP sever.
> We tested DHCP function successfully with  Primary IP address.
> But, When We tested this function with Secondary Ip address in our router ehternet port,
> this DHCP function does not work.

Microsoft's server will give out addresses only to the range that corresponds to its 
interface.   If your server is on the physical wire with the secondaries, you will need
either multiple cards in the server (one for the primary and each secondary) or multiple
servers (one for the primary and each secondary).

FYI, you will get some interesting responses on reboots when the client requests to 
continue using an address.  The client's server will ACK the request while the others
on the other subnet will NAK it.  If a NAK arrives first, the client will go through
the DISCOVER process to "reuse" its address.

It is also possible to manipulate subnet masks on the server to fake it in to thinking
it is processing one subnet.  If this is done, all machines that need to talk with each
other better be using the same subnet mask.

If the server is across a router from the client, then the server will only be able to 
give out addresses on the primary subnet because that is what the router will stamp on
packets sent to the server.