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DHCP subnet

By glenn ·
I have a W2K3 server. The WAN is connected through a Time Warner Telecom device that run on a Class C subnet (255.255.255.0). I cannot use a dual NIC system and have the Internal LAN on the same subnet. Can I reconfigure the scope and use a subnet mask of 255.255.254.0 and expect it to work.

Keep in mind the server is already running on a single NIC with the Class C subnet. I had to set it up that way to get it to work. Is this practical to get the dual NIC arangement to work?

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by CG IT In reply to DHCP subnet

no you can't figure it will work.

reason is that your computer is a host on your ISP network. your computer obtains an IP address and subnet from your ISP. The subnet mask 255.255.255.0, the first 24 bits is the network address and the last 8 bits the host address. When you change the subnet mask by stealing bits from the network portion to create an additional subnet, your not on the same network. Therefore no internet connectivity.

The way around this is to use a router.

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by hozcanhan In reply to DHCP subnet

Glenn , take a low end PC ( or an expensive router with two eth ports ) with 2 NICs( or 3 according to your configuration ) . Put it between TWT device and the server ( or the local lan ) . Load a router application software and start routing . You can have subnets now .

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by CG IT In reply to DHCP subnet

as per your PM question, to use the W2K server and NAT, you have to multi-home the server [2 NICs]. Since you say you can't dual NIC the system [which there really isn't any reason why you couldn't] there is no way around creating subnets by stealing bits and connect to your ISP for internet connectivity unless you use a router[well a managed switch VLAN might work but the administration and configuration is far more problematic than just buying an inexpensive router.

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by jdgretz In reply to DHCP subnet

What are you trying to do?

The assumption here is that you want to connect multiple machines to the WAN via a single connection.

The simple way has been given - purchase a consumer grade broadband router (Linksys, D-Link, etc.) and put it between the cable modem and your LAN. Have either the router or your server be the DHCP Server, but remember to use a static address for your server in either case. Your router will get the address from Time Warner (either a public address or something in the 10.10 area usually) and you can set your LAN to the 192.168.x.x private space.

You can use your server as the router and put two NICs in it - one going to the Cable Modem and the other to a switch where the rest of your machines are connected.

Again, I am assuming a small network here.

Your server will act as the router, provide NAT and DHCP.

The downside to this approach is that it puts your server open to the WAN, and from your question I'm going to assume you are not that well versed in securing a network, especially with a server acting as the gateway to your LAN.

Take the easy approach - use the inexpensice router.

jdg

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