Sunday, January 5, 2014

Windows Server 2012 DHCP Failover Not Adhering to Scope Times

When setting up Windows Server 2012 DHCP Failover you may notice the lease duration provided to clients may not adhere to the lease duration configured on the DHCP scope.  This is by design and a normal behaviour in a DHCP failover relationship.

By default when a lease is first issued to a client, it adheres to the Maximum Client Lead Time (MCLT) value, not the value on the DHCP scope.  This is considered a temporary lease period given by a failover server to a new client.  In addition to providing a temporary lease to client, it specifies the amount of time for which a DHCP lease may be renewed by either failover peer without contacting the other.  It also specifies the amount of time that either DHCP server will wait in a “partner down” state before assuming control of the entire IP address range within the scope.  ( default = 1 hour ).

Maximum Client Lead Time (MCLT) can be found when configuring DHCP failover in the following location in the setup wizard.

 
After the initial lease, when the client attempts to renew its IP address it will then inherit the default scope lease time.
 
Key points to take away:
  • Windows Server 2012 DHCP Failover, an initial lease always = the MCLT (Maximum Client Lead Time)
  • Afterwards the same client will renew and get whatever is defined in the scope definition.
So if you see clients receiving 1 hour leases from DHCP, relax its by design!  They will receive a full lease when they next attempt to renew DHCP.

Sources:

http://technet.microsoft.com/en-us/library/dn338973.aspx
http://tools.ietf.org/html/draft-ietf-dhc-failover-12#section-5.2
http://support.microsoft.com/kb/2831920

3 comments:


  1. product key windows 7 enterprise sp1 , windows 10 pro product key sale , windows7 produck key , upgrade key windows 7 home premium to windows 7 ultimate , vista enterprise genuine keygen , windows 7 ultimate sp2 key , windows 7 home product key generator , office 2016 product key , lvq0oL

    ReplyDelete
    Replies
    1. windows 7 professional sp1 license key , microsoft license key order , windows 10 32 bit activation key , windows 10 activation 10158 , vista anytime upgrade key , windows server 2003 web edition product key , windows xp , buy windows anytime upgrade key online home basic to ultimate , sOy34f

      office 2016 registry purchase

      cheap office 2013 key

      microsoft visio professional 2016 order

      cheap windows 10 product key sale

      buy cheap windows 7 product key

      Delete

    2. office home and business 2010 wholesale , windows 7 ult sp1 keys retail , win 7 activation key , window 7 professional genuine key , buy cheap windows 7 product key , key win 7 professional 32 bit , windows 10 pro key sale , windows 7 professional product keygen , llKDOK

      cheap office 2016 product key

      Online Windows Server 2012 R2 Essentials Product Key

      Cheap Rosetta Stone French Level 1, 2, 3, 4, 5 Set Key Sale

      windows 10 product serial number offer

      buy office 2013 product serial number

      Delete