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DHCP server is not sending out leases.

Hello.  My Windows Server 2012 installation will not send out DHCP leases.  I have reinstalled the Role/Services.  I have made sure its Authorized.  I have setup a new Scope with 125 addresses.  I have made sure the Server/Scope Options point to the correct Router IP address, the correct DNS addresses and is populated with the right Domain Name.

I'm not sure what to try next.  The event logs from the clients say what you would expect, that they are unable to receive a DHCP address.

What steps should I try?

Thanks
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Spencer K
Asked:
Spencer K
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1 Solution
 
Andy BartkiewiczNetwork AnalystCommented:
Did you setup your layer 3 interfaces to talk to the dhcp server? DO you have a firewall that might be blocking?
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masnrockCommented:
What is between the clients and the server? Check to make sure that a switch would not have a reason to filter out your DHCP requests. But also try temporarily moving the DHCP role to another device, and see if that works. If things work with that other device, you may want to check if your Windows Server install is corrupted (or otherwise has antivirus software that's somehow blocking DHCP requests)
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Spencer KAuthor Commented:
Hi guys, thanks for the help.

We had Server 2008 with DHCP installed fine, we upgraded this to Server 2012, which again DHCP appeared to be working fine.  Only after deleting and creating a scope can clients no longer get a lease.  Its strange.

We mostly have layer 2 switches, and did not have any issues before the upgrade in terms of clients instigating the DHCP process.

The firewalls, on both the clients and Server 2012 are both deactivated.

I have even removed the DHCP from the main DC and installed it on another server, making sure the installation process and post installation process completed without any errors.

Does Windows Server 2012 bring anything new in terms of how clients would, or would not, go about asking for a DHCP lease.  Is there any way of testing this on the client,  Wireshark or something to see at exactly what point in the process is failing.

Thanks
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masnrockCommented:
Wireshark would be the best way to go about seeing what's going on. Based on what you were mentioning, I want wondering if the server was even getting the request to begin with. You would need to connect systems to the network, so that they would send DHCP requests. If those aren't flowing like they should be, then that's an issue. Otherwise, it becomes a matter of whether the server is actually receiving the requests. And if so, is the DHCP server sending responses like it should be?

I have even removed the DHCP from the main DC and installed it on another server, making sure the installation process and post installation process completed without any errors.
Did things work when you did this? Obviously doesn't solve the original issue, but helps to be sure that the problem is isolated to one server. And does the server have any other issues?

Are you switches managed or unmanaged? That might be a point worth digging into if managed.
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Spencer KAuthor Commented:
Hi guys, I installed it on another server, made sure I removed the old server entry, using ADSI edit, from within the NetServices section and it worked fine.  

I would still like to know why, on the original server, it did not work correctly.  Still, the problem is fixed.
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masnrockCommented:
What is installed on the problematic server? It's still sort of wide open on what the cause can be.
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Spencer KAuthor Commented:
The original server was our main Domain Controller; this contains DNS, AD etc..  

Before we updated the server to 2012 we could delete and create DHCP scopes without issue, clients would start populating with DHCP addresses instantly.  

thanks
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masnrockCommented:
Just to avoid repeating things you've already done, did you already try removing and reinstalling the DHCP role? I know we mentioned the possibility of you monitoring traffic, did you ever check whether the problematic server actually responded with any sort of DHCP replies?
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Spencer KAuthor Commented:
Hi, yes - I removed the role, recreated the scopes but to no avail.   I didn't get time to sniff out any packets though. Was on a timer to get it working before the kids come back from half term.
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masnrockCommented:
What sort of virus/malware protection is on that particular server? Wonder if removing/reinstalling it would've addressed the issue.
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