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Connecting to a default gateway on a different subnet

I am setting up a test domain at my office. I have an old Windows server with 2008 as a new domain and new forest. We use a B Class subnet for our main network. I would like to configure this test domain to use a straight C network (/24).

I set up the new server to use 192.168.240.5/24. Obviously, it cannot reach our default gateway: 172.16.0.1/16.

I was told that I could list the test server's ip as the default gateway (in the server's TCP/IP connection settings) and manually add a route from the server to the default gateway. This would, theorectically, enable connectivity to the default gateway.

I've tried "route add 0.0.0.0 mask 0.0.0.0 172.16.0.1", "route add 0.0.0.0 mask 255.255.255.0", and "route add 0.0.0.0 mask 255.255.0.0 172.16.0.1". No luck.

I have verified internet connectivity when the server is on the standard (B class) subnet.

Is what I am attempting possible? Any help would be appreciated. Thanks in advance.
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ecshelpdesk
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ecshelpdesk
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1 Solution
 
Ken BooneNetwork ConsultantCommented:
The default gateway and any other routes default or not that you configure must have a next hop ip address of something on THAT devices network.   There are special cases where you could do recursive routing, which is what it sounds like you were told to do.  But even so at some point in the recursion it must resolve to a route that has a next hop of something on your network.  That is why its called a gateway.  It is a gateway that lets you go to another network.  So at some point you must have a layer 3 interface on the new network that can route to the existing network.
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ecshelpdeskAuthor Commented:
Thanks! That got me started on the right path:

I found an old router, disabled DHCP, plugged in the server and a test computer into two of the ports, and plugged a cable from our main network into the "Modem" slot. The router picked up a dhcp address for the WAN and I statically set the two terminals to use the new router as a default gateway. It's working fine.

Follow up, though:

I disabled DHCP because I was concerned the router would start assigning addresses over the WAN. But, thinking about, that does not seem likely. The router's DHCP service (I believe) would only be applied "downstream". It would only apply to the wireless broadcast and to client ports. It would not try to assign dhcp through the wire connected to its "Modem" port (the WAN). Does that seem correct?
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Ken BooneNetwork ConsultantCommented:
Not sure what the router is but that sounds right.  It typically would only act as a dhcp server for the local lan and local wireless clients.
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ecshelpdeskAuthor Commented:
Great, thanks!
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