zero free leases

David W. Hankins David_Hankins at
Thu Jun 28 19:58:09 UTC 2007

On Tue, Jun 19, 2007 at 12:25:58PM +0800, Usman Wahid wrote:
> I had the 'peer holding all free leases' issue recently with one of  
> our IP range. Range consisted of 507 addresses, out of which, 3 were  
> active, 0 were free, 256 were expired, 14 were released and 234 were  
> in backup state on one of the two DHCP servers. I am using ISC DHCP  
> version 3.0.4 in a failover environment consisting of two servers.  
> Lease time for the problematic servers is 2 hours. Should I increase  
> the lease time to avoid the problem in future? Alternatively, what  
> other options can considered? Thanks in advance for any help.

The 'expired' leases become 'free' after the peer server acknowledges
the state change.

The state change may not be getting acknowledged for many reasons;

1) Servers not communicating - not in 'normal' state.  Extended
   runtime even in communciations-interrupted state will not reclaim

2) Server clocks not synched - the peer understands the leases are not
   expired and rejects the update.

3) The peer is not configured with the address ranges.

...probably other reasons.

Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
Why settle for the lesser evil?
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins

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