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I have a Windows 2012 Server with 2 NICs running as a DHCP server. Each NIC is connected to a different subnet. I'd like to run DHCP service on each subnet from the same server. Is that possible?

I've got two scopes set up, and the DHCP server says that it's binding to both NICs (their IPs, actually). But the server is only passing out leases on the first NIC.

The machine is a domain controller, which I know is undesirable, but it's the only machine available right now.

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  • Do you have a cope set up for the network that each NIC is connected to? Do you have DHCP clients connected to both networks?
    – joeqwerty
    Apr 23, 2014 at 15:09
  • I don't understand the setting up a cope part, but I think each NIC is configured properly. I can ping the server on the NIC that's not working for DHCP, and I can RDP into the box on that NIC as well. I did try to use a DHCP client on both networks.
    – Alex S
    Apr 23, 2014 at 15:56
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    In order to serve DHCP clients on each network you need to have a DHCP scope setup for each network. If, for example, you have a NIC at 1.1.1.1/24 for network 1.1.1.0/24 and a NIC at 1.1.2.1/24 for network 1.1.2.0/24 and you only have a Scope for 1.1.1.0/24 then clients connected to 1.1.2.0/24 will not get an ip address because there is no Scope for the 1.1.2.0/24 network. You need to have a Scope set up for each network that the server is connected to.
    – joeqwerty
    Apr 23, 2014 at 16:02

2 Answers 2

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Yes its possible, but a better solution is to have a single interface, especially on a Domain Controller, and configure your routers to forward the DHCP broadcast from the clients to the DHCP Server. In Cisco terminology this is called an IP Helper. It's also commonly referred to as DHCP Relay.

What are you going to do when you get a third subnet? What about a 10th subnet? You can't keep adding interfaces.

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  • I'm taking what everyone is saying about DHCP relaying to heart. I'll try to get that done.
    – Alex S
    Apr 23, 2014 at 15:46
  • This did work, as everyone said it would.
    – Alex S
    Apr 23, 2014 at 17:13
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Just assign your IP addresses to your NICs, the DHCP server will hand out addresses in the proper scope based on which NIC it receives the requests from.

Here's the TechNet article on relay agents: http://technet.microsoft.com/en-us/library/cc779610(v=ws.10).aspx

That will help with understanding MDMarra's answer, which is preferable to what you're currently doing.

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  • I understand that routing is better, but it's a little harder for me to set up, as someone else controls the router.
    – Alex S
    Apr 23, 2014 at 15:29
  • May be worth getting them involved. If they aren't playing as a team (which I assume you all are) then I would just report him to your manager. Better to adhere to best practices for scalability, which will save you both work in the future if anything has to change.
    – MagnaVis
    Apr 23, 2014 at 15:31
  • @AlexS - so work with that someone to accomplish this correctly.
    – TheCleaner
    Apr 23, 2014 at 15:31
  • If they aren't playing as a team (which I assume you all are) then I would just report him to your manager. - Well that seems a little extreme and premature at this stage. We have no idea what the situation is so a suggestion to work with the routing team is sufficient. No need to bring company politics into it at this point.
    – joeqwerty
    Apr 23, 2014 at 15:40
  • It's not that sort of thing. It's more of a time crunch/I'd rather solve it on my own situation. But everyone is saying that there's a right way to do it, so that's what I'll do. I'd still like to know why just using the NICs isn't working.
    – Alex S
    Apr 23, 2014 at 15:47

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