Dual NICS - Windows 2000 Advanced Server

By robert.gloess ·

I have a major issue with a network server at the moment. It has dual NICs in, on imbuilt compaq nic and one Intel pro 10/100. I have wired it so the imbuilt nic is to use a wan connection though a adsl wireless router and the other goes into a cisco catalyst to the network. Both have seperate IP addresses, staticly assined. The problem is that the server wants to use the NIC connected to the cisco switch for it's internet connection and not the one to the router. As it is the proxy server it is required for internet acccess, so to solve the problem i have put a bit of cat5e between the adsl router and the switch, any tips or help would be extremely helpful as this really is strating to get annoying!


Rob Gloess

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more info needed

by jfitzct In reply to Dual NICS - Windows 2000 ...

where are you trying to access the internet from, this server or the internal network?

is there a default gateway entry on the internal nic of the server?

are the statically assigned addresses on the server on different sub-nets?

where does the computer you are trying to access the internet from look for dns info?

what is the default gateway of that dns server?

what proxy software are you running?

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NIC/Routing Configuration

by AndyMcK In reply to Dual NICS - Windows 2000 ...

Hi Rob,

Sounds like you have a default route on the server pushing all extneral traffic through the internal nic. The adsl router probably has a route pushing everything not internal out onto the net and is seeing this traffic on the switch.

You should have each nic on the server on different subnets; your wan nic should be on the same subnet as the internal nic of your adsl router; your server's internal nic should be on the same subnet as the rest of your network. You'll also need to have some form of routing configured (see Routing and Remote Access) to point all internal traffic through the internal nic and everything else through the wan nic.

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by robert.gloess In reply to NIC/Routing Configuration


Thanks for helping.

I am trying to access the internet from the internal network. Although these are set to look for the internet through the server, so the server must have a internet connection, abviously! I will have to check up on the DNS server, i have configured it, but not propbally, one of the things on my to-do list. The server has static IPs on both nics, and .70 is the connection to the adsl router and .71 to the cisco switch. There are both on the subnet. The server is running proxy plus 3. Its not the best but it does a great job, when i can get this problem fixed! I am pretty sure that the DNS server is the probelm, or the server is not running some sort of service that it should be. I iknow this because when i bypass the server with a simple patch cable from the router to the switch everything goes fine, but that defeats the objective..

I hope i have covered everything you asked for, if not i will draw up a diagram on visio..



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NICs and Subnetting

by AndyMcK In reply to Update

OK, first thing to be clear on is that is not a subnet, it's a subnet mask. A subnet mask is used to define a subnet. As an example, to put these NICs on different subnets use settings such as:

IP Address:
Subnet Mask:

IP Address:
Subnet Mask:

Notice the difference in the IP addresses. It's *definately* worth your while to look up IP subnetting on Google to get a fuller understanding of this, it's essential if you're going to maintain your network properly.

At the moment both the servers' NICs are on the same subnet. You need to change this for your setup to work correctly. Once you have them on different subnets then you will have to configure routing between the two NICs. Something such as Routing and Remote Access will do this.

I'd suggest your plan of action to be:

1. Read up on IP addresses and IP subnetting, this will make everything else easier. There's lots of info on this online, just Google.

2. Get both NICs on different subnets with your internal NIC on the internal network's subnet and your adsl NIC on the same subnet as the internal address of your modem.

3. Setup routing between the NICs using something like Routing and Remote Access.

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by jfitzct In reply to NICs and Subnetting

what Andy said.

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by robert.gloess In reply to NICs and Subnetting


The amount of times i have had subnetting explained to me by various, still can't get a 100% grip of it. Have got the great 9 - in - 1 for dummies book on networking, great book by the way, would recommend it to anyone who wants to get into the networking world, theres a chapter on subnetting, never really took interest as it wasn't really needed untill now! Just got away with i know that has a subnet mask of and has something like 254 usable addresses.

Cheers, will read that chapter later and get back to you all if it works!

thanks again,


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by AndyMcK In reply to Thanks

Subnetting is just one of those things, eventually you'll read a document and it'll just click. Once that happens it'll all be easier :) There's a decent article on this site that might be worth a look for you:

Good luck!

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by robert.gloess In reply to Dual NICS - Windows 2000 ...

Jus a note to say thanks, its all done now, and fully tested. i made the internel nic set as in the same subnet as the adsl router and the other nic, the server also does dhcp dns etc all fine.

Thanks for your help..

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internal NIC same subnet as router

by CG IT In reply to Thanks

you mentioned that you changed your internal NIC to the same subnet as the ADSL LAN, what did you do with the external NIC?

From the posts, it appears that you don't need two NICs as the internal NIC is configured to send traffic not destined for the local network out to the default gateway which would be the router [if you configured it on the same LAN as the ADSL router].

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Internal Nic

by robert.gloess In reply to internal NIC same subnet ...

Just to make sure, all the nics are internal, i just call the internal nic the one that is built onto the motherboard of the server. The 'external' Nic is the one on the PCI bus.

I set the internal one on the same subnet as the ADSL router, 192.168.1.x. The 'external' nic was set on the 192.168.0.x subnet, it's actual ip is The PCs are connected to a CAT which is then in turn connected to the NIC (external). The server is acting like a router, and is set up as a proxy/firewall. There is no other connection between the CAT and the ADSL router. It all seems to work fine now, DHCP, DNS proxy ec, just the domian controller to sort out now!...


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