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DHCP Server deletes reservations

DHCP Server deletes reservations

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DHCP Servers in Windows Server 2008 R2 are deleting reservations,   in certain instances, without user intervention.      If two DHCP Servers in split scope configuration are configured with  identifical reservations,  both of these servers may respond to client requests for a lease.   The client accepts a reserved IP address from one of the servers and the other server, automatically (and incorrectly) deletes the reservation on it's server.

 A hot fix is available for this issue.   

Team Networking


    Above the discussion about the issue!

    Best regards,

    Arian van der Pijl!

  • Glad the hot fix is available.   Not to be too critical, but how could this have possibly passed testing?   Using two DHCP servers and a shared reservation is a standard configuration and we found this bug within an hour of testing our new DHCP config on 2008R2.   Just curious how this slipped through?    

  • I applied the hotfix and reboot the servers last week. It seems that the problem was corrected but something bizarr happen last night after the domain controller windows update was applied and rebooted. The DHCP server lost the router and the lease duration settings in all scopes "20".

  • John,

    I agree that this should not have slipped through.

    We have now added more QA coverage around reservations.

    We also continue to look at QA processes in a constant endeavour to improve product quality.

    Thanks for your feedback.


    Team DHCP

  • Well I have a similar issue and I am not sure the hotfix wil fix the problem.  I only have the scopes for this server on one server, but I have a user that cannot see the DHCP Reservations.  He has full control of DHCP, and can create a reservation but when he refreshes the reservation disappears.  He is using WinXP with MMC 3.0 and the DHCP server is on a Domain Controller that is running R2.  From my console on Win7 MMC 3.0 I can see all the reservations.

  • Hi Dominic,

    Using a down level (lower version) client to manage higher version server is not supported.

    To manage a Windows Server 2008 R2 DHCP, you will need to use MMC from Windows 7 or Windows Server 2008 R2.



    Team DHCP

  • Interesting issue here. We have IP phones from Mitel that work fine with a 2003 DHCP server, but when plugged into our test environment, 2008R2, they fail to obtain an address. If I create a reservation for the phone, then it picks up that address just fine, but won't get an address without a reservation.

    Any idea how to trouble-shoot this kind of problem?

  • Mark,

    Have you tried packet captures on the DHCP server. You should also look at the DHCP server audit log for messages for a the MAC addresses of the specific IP phone.



    Team DHCP

  • Mark,

    Creat a new string > Scope Option

    Vendor class:

    User class: Default User Class

    001 Mitel

    Data Entry

    String value:;sw_tftp=Mitel server IP;call_srv=Mitel server IP;dscp=46;vlan=Vlan ID;l2p=6

  • We have faced similar issue with 2008 and not R2, is it also known issue?

  • There have been no reports of this issue (deletion of reservations) on Windows Server 2008.

  • I have W2008R2 SP1 and splitscope is deleting reservations. Downloaded the hotfix, but popup says it is not for this computer.

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