Two Gateways

if both ip address are on the same subnet, then two different gateways would be on the same subnet as well. if that is the case, clients from other other side of the gateway would be from a foreign subnet and thus won't be able to ping your server.
ip address of the gateway should be part of a different subnet and multihomed (with another nic) to your pc configured for your subnet.

hope this helps.

well,in short, two routers connected to same network, but each router is connected to a different branch,I can't change the subnet mask, both must talk with my local network.

I have an idea: on the second interface I can create a new subnet, and let the 2nd adapter on that network and let the router do its job and route between them.. u think it will work like that?

One last thing!! why wwe can put two gateways on NT server, while it never shift to the other if the 1st failed. ( I tried it)

We have this same situation here. What happens is that NT does not like the idea of 2 gateways. It is not supported I think.

So what we do is leave the gateway on one card but leave it out of the second card and use - route add- command to add the second network via the intended second gateway. This works perfectly. Pls dont forget to use a -p at the end of the route add command.

Thanks

On the machine with the two NICs, use a ROUTE.EXE to direct traffic out the appropriate NIC.
For example, lets say NIC #1 is 192.168.1.1, and you want it to respond to clients on 192.168.11.0.
NIC #2 is 192.168.1.2, and you wnat it to respond to clients on 192.168.21.0.

On the machine with two NICs, from the command prompt:
c:\route.exe -p add 192.168.11.0 mask 255.255.255.0 192.168.1.1
This tells the machine to send all traffic destined for your 192.168.11.0 network out the NIC with address 192.168.1.1. The "-p" makes the route persistent after reboot.

For the second route:
c:\route.exe -p add 192.168.21.0 mask 255.255.255.0 192.168.1.2

My colleagues, here is what happened:
I tried the route command as u mentioned on the exchange server, but as u wrote it gave an error add route failed: 87, anyways, even if it worked,another unexpected problem came out, users on my local network was unable to check their email anymore,mail sever not found,although they can ping the first NIC normally,after they ping they can check email,strange!!! anyways, best solution: I removed the 2nd NIC,configured the router to route all trafic to the 2nd one if the destination was unknown. BINGO.