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DHCP Server not leasing IPs.

Posted on 2013-05-21
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Last Modified: 2013-08-03
Hi,

I have two Windows server 2012 VMs that are DC and DNS servers. I set up DHCP on one with scope and configured fail over to the other VM that is also a DC and DNS server on another HYPER-V host.

After 3 weeks or so, they stopped leasing IP address. There where no errors and warning in either event Logs. Reboots etc.. made to difference.

In the end I had to put DHCP on a 2003 Server and have that leasing out the IPs.

TROUBLESHOOTING;
I removed the role on both 2012 servers and rebooted. I then added the role on DHCP01 and saw that the scope database was still intact with exclusion, reservations etc.. I did not set back up the failover. I unauthorised the 2003 and authorised the 2012. All was fine for two hours or so and again no IPs. Back to 2003. In event logs there was database backup issues for DHCP. Forums stated AV and to exclude the DHCP folder. that was there already but stopped AV anyway. Switched back off 2003 and back on 2012, but the same after a while with no event logs.

I then 'moved' the role from DHCP01 to the other 2012 server, DHCP02, but the same would happen after a few hours with no errors.

The DHCP01 VM and DHCP02 VM are on different Hyper-V Hosts.

What can cause this to happen? I have other customers with server 2012 DHCP server with no issues.?

-Thanks,

GNS.
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Question by:ggntt
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Expert Comment

by:Nagendra Pratap Singh
ID: 39186499
During that time, did you install a new firewall etc?

Also do you have a spare 2012 VM where you can install DHCP and some packet analyzer?
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Author Comment

by:ggntt
ID: 39189010
Hi npsingh123,

No new firewall at all.

I have the two host servers!


-GNS!
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LVL 23

Expert Comment

by:Nagendra Pratap Singh
ID: 39189807
Create a small vm and install dhcp + packet analyzer on it.

Installing on host will not work because it has different settings.

Few from the following page may be good for windows 2012.


http://4sysops.com/archives/free-packet-sniffers-for-windows/

This has the process

http://www.youtube.com/watch?v=WztEbO0uiiQ
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Author Comment

by:ggntt
ID: 39201461
Hi All,

An update.
I Installed a new Win2012 VM and added the DHCP role. THen with wireshark and followig the link from npsingh123, it was leasing out IPs and the other server was not. However after 2 hours it was still going strong and after 3.5 hours still was leasing IPs. ( other time it stopped after 2 hours ish) I then started to add in a deny list of all the mobiles phones that access the network via WAPs, and within an hour of activating the deny list, the server stopped leasing IPs. I then disabled "Deny" and all is working again.

Any ideas?

Thanks,

-GNS
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Accepted Solution

by:
ggntt earned 0 total points
ID: 39363342
The answer was that the filter option had the Deny all but the list ticked, with nothing in the list. Once that was unticked, all was good again.
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Author Closing Comment

by:ggntt
ID: 39378819
The answer was that the filter option had the Deny all but the list ticked, with nothing in the list. Once that was unticked, all was good again.
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