DHCPd sending lease expiration of 3600 seconds

David Forrest drf at maplepark.com
Wed Feb 18 00:39:47 UTC 2009

On Tue, 17 Feb 2009, Jeff Haran wrote:

>> -----Original Message-----
>> From: dhcp-users-bounces at lists.isc.org
>> [mailto:dhcp-users-bounces at lists.isc.org] On Behalf Of Geoff Sweet
>> Sent: Tuesday, February 17, 2009 3:47 PM
>> To: dhcp-users at lists.isc.org
>> Subject: DHCPd sending lease expiration of 3600 seconds
>> On my CentOS 5.2 system I am setting up some network services for our
>> corporate environment. DHCP works great EXCEPT that clients
>> are getting
>> a lease from the server that expires in 3600 second even though the
>> config says otherwise. Here is my config:
>> #####
---------> snipped
>> # lease expiration
>> default-lease-time 86400;
>> max-lease-time 86400;

>> I can see clearly in a WireShark network trace that the
>> server responds back with the lease marked as expiring in 1
>> hour. It's like the service is ignoring the default-lease and
>> max-lease settings. Any thoughts?
>> Thanks,
>> Geoff Sweet
> I see something similar with dhcpd 4.0, except that my problem is trying
> to get it to assign infinite leases.
> Wireshark showed dhcpd assigning long leases (I believe it was the
> number of seconds until the Unix Epoch overflows 2^^31 seconds in 2038),
> but I could not get it to assign leases of infinite length (all 1s in
> the appropriate option value). This keeps the DHCP clients receiving
> these leases executing but blocked on a long timeout in select() in
> order to start renewing some day in the distant future when they could
> otherwise terminate. The problem remains.
> I posted to this group, but never got a response.
> Jeff Haran
> Brocade

It seems sometimes the client requests a shorter lease.  If you want a 
longer lease assigned than the client requests, just assign a min-lease
like this:
min-lease-time 85200;

along with your max and default of 86400 and you'll get leases in the 
window of 85200-86400.

St. Louis, Missouri

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