Permanent DHCP leases configured in the DNS / DHCP management consoles expire in 1943

  • 7009550
  • 11-Oct-2011
  • 27-Apr-2012


Novell Open Enterprise Server 2 (OES 2) Linux Support Pack 3
Microsoft Windows XP Professional


After configuring a static (permanent) lease via the DNS / DHCP management console, the Windows XP machine receives an address with a lease time that expires in 1943.


On older DHCP reservations, change the Lease Type from "permanent" to "Timed"

1.  Open the DNS / DHCP management console.
2.  Highlight the host reservation in the left panel
3.  Select the "lease" tab
4.  Change the box from "Permanent" to "Timed"
5.  Modify the "Days" field to show 365

This will result in yearly leases that will only attempt to renew every six months.

Additional Information

The 'lease time' that is given via the 'maximum lease time' parameter is:  2147483647 which translates to 7f ff ff ff.  According to the RFC (2132) DHCP Option 51 is a 32-bit unsigned integer.  2147483647 is the maximum value that a 32-bit unsigned integer can represent.  So the lease time being handed out is perfectly valid, however the XP machine (and potentially other devices that get DHCP addresses) may not interpret this large of a number properly, and roll over the calendar date (resulting in an address from 1943)