Server 2012 R2 DHCP

Posted on 2016-08-30
Last Modified: 2016-09-01
I have a physical server running 2012 R2 (replacing an older server running Server 2003), and I'm trying to use one of the NICs for a Ghost network. The old server runs to an unmanaged switch, and we connect PCs to this network to PXE boot into Ghost. However, we cannot get DHCP to run when connecting the new server to the network, and cannot even ping back and forth. We are disconnecting the cable from the old server and are using a different port on the switch, but we can't get this NIC to communicate with any other machines on the network, much less obtain an IP address. Is there something simple we're missing, i.e. firewall issue, NIC configuration, DHCP configuration, etc?
Question by:maximjon
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LVL 21

Expert Comment

ID: 41777116
What happens if you configure the NIC statically?  Are you able to ping other devices?  That will help you decide if it is a DHCP issue or not.

It sounds as if there is a problem with the NIC, the cable, or the port on the switch.  Do either of the lights on the NIC light up when you connect the cable?  What about the lights on the port on the switch?

Author Comment

ID: 41777972
We've actually been able to ping back and forth from a client with a static IP once we tweaked the firewall. The NIC looks okay, and the ports on the client and switch all light up as they should. At this point it definitely looks like a DHCP issue.
LVL 21

Expert Comment

ID: 41778359
What is doing DHCP?  Can the server in question ping the DHCP server when using a static IP?  If you would post the results of ipconfig /all from the server in question when configured for a dynamic IP address it would be helpful.
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Author Comment

ID: 41778514
It's a server with Windows Server 2012 R2, with a static IP address running DHCP. Everything looks like it's configured correctly, but we're not sure where to double-check. We're trying to get it to hand out a DHCP address to a client running Windows 7 at this point. There's an unmanaged switch in between, and the server will eventually be used to push Ghost images. We have an older server running Server 2008, which has been able to distribute addresses without any issues. We don't have them on the (very limited) network at the same time, and there are no other devices connected.

If we set a static IP address for the client, it and the server can ping each other. However, when we set the client to DHCP, it gives an APIPA IP address (169.254...) and cannot contact the server.
LVL 21

Accepted Solution

CompProbSolv earned 500 total points
ID: 41778565
OK.... so I misunderstoodd the original post.

You have set up DHCP on the Server 2012 box and it isn't handing out addresses.  If the workstation has a static address then it can ping the Server.  This says that there are no physical obstacles (bad cable, switch, etc.) to DHCP working properly.

It is almost certainly a setting in the DHCP server configuration on the Server 2012 box.  Are you comfortable that you've set it up correctly?  Have you authorized it?  Do you have it listening on all NICs?

To test if it is a firewall issue, turn off the firewall (temporarily) on the Server and run ipconfig /release
ipconfig /renew
on the workstation and see if it gets an IP address.

Author Comment

ID: 41779719
We found the issue, it was a conflict with authorizations within AD, even though this was for a separate LAN. Thanks for pointing us in the right direction!

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