[CentOS] dhcp lease-time

Timothy Murphy gayleard at alice.it
Thu Jan 5 13:03:30 UTC 2012


John Hodrien wrote:

> On Thu, 5 Jan 2012, Timothy Murphy wrote:
> 
>> Why is the default lease-time set to only 10 minutes (600 seconds)
>> in /etc/dhcp/dhcpd.conf (CentOS-6.2) as distributed?
> 
> I assume the dull answer is: because that's what Redhat set it to.

Let me re-word the query for you:
Why does Redhat set the default lease-time to only 10 minutes (600 seconds)
 
>> Why is not set to a much longer time?
> 
> What length do you think the correct default should be?

I see various much longer times on the web, eg (at random)
<http://www.yolinux.com/TUTORIALS/DHCP-Server.html>
---------------------------------
        default-lease-time 21600;                            
	# Amount of time in seconds that a client may keep the IP address
        max-lease-time 43200;
---------------------------------

>> Is there any disadvantage in doing that?
>> Or conversely, is a short lease-time safer in some way?
> 
> Short lease times work better with very transient devices, since the IP
> address is returned to the pool much faster when a machine disconnects but
> doesn't release the DHCP lease.

I suppose this might make sense if more than 100 devices
might join the network.
This would be unlikely in my case (a home network),
where almost all the devices have static IP addresses.


-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College Dublin





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