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DHCP Load Balance Failover RRS feed

  • Question

  • Hi

    I would like to confirm what happens to the DHCP IP leases on a partner server when i remove a load balance (50-50) failover relationship?

    Currently the primary DHCP server has lost contact with the partner DHCP server, so i need to delete and recreate the failover, but before I do I would like to know what happens to currents leases on the DHCP server the scope will be removed from.

    Thanks in advance.

    Wednesday, September 7, 2016 11:08 AM

Answers

All replies

  • Hi,

    In load balancing mode, when a DHCP server loses contact with its failover partner it will begin granting leases to all DHCP clients. If it receives a lease renewal request from a DHCP client that is assigned to its failover partner, it will temporarily renew the same IP address lease for the duration of the MCLT. If it receives a request from a client that was not previously assigned a lease, it will grant a new lease from its free IP address pool until this is exhausted, and then it will begin using the free IP address pool of its failover partner. If the DHCP server enters a partner down state, it will wait for the MCLT duration and then assume responsibility for 100% of the IP address pool.

    REF:DHCP Failover Events and Performance

    https://technet.microsoft.com/en-us/library/dn338988(v=ws.11).aspx


    Best Regards,
    Cartman
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    Thursday, September 8, 2016 6:46 AM
  • Thanks for your response Cartmen Shen. I have followed your advice to change the fail over to partner down, but i see the following error 'The DHCP failover relationship does not exist.'

    I basically want to remove the scope from the fail over partner, keep the scope on the primary, then create a brand new scope on the partner. End game being 2 DHCP servers with 2 seperate\individual scopes;

    Server A scope - 200.202

    Server B scope - 203-204

    How do you best advise me to do this with minimal impact on the current failover partner leases?

    Many thanks

    Thursday, September 8, 2016 1:25 PM
  • Hi,

    Check status of the failover relationship..............Failed.
    The DHCP Server service is not running on the target computer.
    Deconfigure failover failed. Error 1722. The DHPC server is not running on the target computer.

    Is this error you encountered?If it is the case,please check this thread:

    https://social.technet.microsoft.com/Forums/office/en-US/a4e94973-955f-4090-9332-46742f7b2b32/how-do-you-remove-a-dhcp-failover-in-windows-server-2012-when-the-dhcp-manager-and-powershell?forum=winservergen


    Best Regards,
    Cartman
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    • Marked as answer by MikeRicks Wednesday, September 14, 2016 7:12 AM
    Friday, September 9, 2016 4:05 AM
  • Hi

    Yes this is part of the scenario that is happening to me. 

    So I need to run the below...

    Remove-DhcpServerv4Failover -ComputerName *PCNAME -Name *FAILOVERNAME -Force

    Can you confirm that this will delete the failover and scope from the secondary server ONLY?

    I need the scope to stay active on the primary server...

    Thanks.

    Tuesday, September 13, 2016 2:07 PM
  • Hi,

    Typically,it will.In case of any unexpected situation,I suggest you backup the DHCP database before you do that.


    Best Regards,
    Cartman
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    Wednesday, September 14, 2016 5:16 AM
  • Running the powershell command worked as expected running from the primary DHCP server, removing the broken failover.

    Thanks for your help Cartman!

    Wednesday, September 14, 2016 7:12 AM
  • Hi,

    Glad to hear that,if you have any other question,please feel free to ask here.


    Best Regards,
    Cartman
    Please remember to mark the replies as an answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Thursday, September 22, 2016 4:34 AM