DHCP Server not assigning IPs

Posted on 2011-09-24
Medium Priority
Last Modified: 2012-05-12
Dear Experts,

I have Windows Server 2008 R2 installed DHCP Service. DHCP rang is ( to and lease timing is (8 hours). this rang is about 190 IPs and total workstations in my company are 150. This DHCP Server was working fine for last 4 months. but now its not assigning IPs automatically what can be the reason. is there any release timing issue or any other reason can be.
Please help me to fix my this problem.

Question by:nainasipra
LVL 57

Expert Comment

by:Mike Kline
ID: 36594452
Are you using ip helper addresses or firewalls that may have changed.

You can check for rogue DHCP servers   http://blogs.technet.com/b/teamdhcp/archive/2009/07/03/rogue-dhcp-server-detection.aspx

Go through the DHCP events on your server, another tool that may help (this one I haven't used myself)  http://blogs.technet.com/b/teamdhcp/archive/2009/03/20/tool-to-read-dhcp-server-events-for-windows-server-2008-r2.aspx

Did anything change on your network at all?  Odd that it stopped working all of a sudden.  Network traces using wireshark or network monitor may also help.


LVL 39

Accepted Solution

Krzysztof Pytko earned 2000 total points
ID: 36595132
Besides Mike suggestions, I would also check if someone (other administrator?) didn't deactivated scope or unauthorized DHCP server? These 2 things are necessary to get DHCP working.

Please verify also if your IP pool is not saturated in 100%, maybe there are no free IPs to issue?
Check also if your DHCP database is not corrupted?

Additionally, please open DHCP management console, select IPv4 node, click right mouse button and choose "Reconcile All Scopes" and "Verify" button.

And as the last one thing. restart DHCP Server service or reboot server

LVL 10

Expert Comment

ID: 36595730
Along with the above comments I suggest you to exclude DHCP database from real time antivirus scan otherwise it leads database corruption frequently.


Expert Comment

ID: 36596613
Also, check that you don't have a reservation that's the same as the scope - If you have a reservation for, the server won't assign IPs, and it can take a while for the effects of that to show.  
LVL 39

Expert Comment

by:Krzysztof Pytko
ID: 36915818

any progress in your issue, new facts?


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