Reducing the value of max-lease-time and default-lease-time

John Hascall john at
Tue Aug 17 14:23:18 UTC 2010

You'll basically double the number of leases you issue.
If your hardware is lacking this may be an issue.

The semester doesn't start until next week and we're
already doing over a million leases a day,
so with good hardware you can do a lot.

(At this point most of our students are carrying around
at least one and likely more WiFi-enabled devices and
each building's network is a separate subnet, so we see
a lot of lease churn at the top of every hour during
the day.


John Hascall, john at
Team Lead, NIADS (Network Infrastructure, Authentication & Directory Services)
IT Services, The Iowa State University of Science and Technology

> I help run the dhcp servers that serve several thousand hosts. I've been 
> considering turning down the max-lease-time and default-lease-time by 
> half their value so that an upcoming migration to another set of DHCP 
> servers will have more flexibility if we need to switch back.
> Is there anything I should be considering before changing these values 
> or should I be ok?  I looked around online for any warnings about doing 
> this but couldn't find anything.  Also, I'd be doing this lease time 
> change a few days in advance of the switchover so it should be plenty of 
> time for all the hosts to pick up the new lease times.
> Thanks,
> Mark
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