Why is the default lease-time set to only 10 minutes (600 seconds) in /etc/dhcp/dhcpd.conf (CentOS-6.2) as distributed?
Why is not set to a much longer time? Is there any disadvantage in doing that? Or conversely, is a short lease-time safer in some way?
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.
Why is not set to a much longer time?
What length do you think the correct default should be?
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.
jh
On 01/05/2012 09:54 AM, 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.
Why is not set to a much longer time?
What length do you think the correct default should be?
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.
Also, there should be distinction between default and max lease time. DHCP server uses default lease time too force DHCP client to "chek-in" in that time period. If device does not respond, then DHCP server will reuse that IP.
Max lease time is used to allow DHCP client so the traffic is lesser and after that time DHCP client will ask for renewal of the IP.
Ljubomir Ljubojevic wrote:
Also, there should be distinction between default and max lease time. DHCP server uses default lease time too force DHCP client to "chek-in" in that time period. If device does not respond, then DHCP server will reuse that IP.
Max lease time is used to allow DHCP client so the traffic is lesser and after that time DHCP client will ask for renewal of the IP.
When is the max lease time used, as a matter of interest? Looking at /var/log/messages on my home server, it seems each device is checked after half the default time, ie every 5 minutes.
On Thu, Jan 5, 2012 at 7:07 AM, Timothy Murphy gayleard@alice.it wrote:
Ljubomir Ljubojevic wrote:
Also, there should be distinction between default and max lease time. DHCP server uses default lease time too force DHCP client to "chek-in" in that time period. If device does not respond, then DHCP server will reuse that IP.
Max lease time is used to allow DHCP client so the traffic is lesser and after that time DHCP client will ask for renewal of the IP.
When is the max lease time used, as a matter of interest? Looking at /var/log/messages on my home server, it seems each device is checked after half the default time, ie every 5 minutes.
Devices aren't 'checked' by the server. It is up to the client to renew the lease and they normally try when the lease is halfway up if they are powered on and connected. But the IP stays reserved for the MAC address that has it until the max time and the client will normally request (and get) the IP it had last time unless it has been given out to something else.
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.
On 01/05/2012 07:03 AM, Timothy Murphy wrote:
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)
That is the correct question. The default upstream is 24 hours.
-
John Hodrien -
Johnny Hughes -
Les Mikesell -
Ljubomir Ljubojevic -
Timothy Murphy