A Question on Dynamic DHCP/DNS IP Lease Renew

[Glenn Satchell]

On Fri, September 30, 2016 5:34 am, Frank Price wrote:
> On Thu, Sep 29, 2016 at 3:00 PM, Simon Hobson <dhcp1 at thehobsons.co.uk>
> wrote:
>
>> > 2. Should I add "reserved;" to both of them?
>>
>> Only the last - the others aren't used.
>>
>> > 3. Can this be done without restarting dhcpd?
>>
>> Only if you use OMAPI.
>> If you don't use OMAPI you must stop the server before editing the file
>> -
>> otherwise it may append to it while you are editing, or replace it
>> entirely
>> if it does it's cleanup routine. You have to stop and start the server
>> anyway for it to read the file during startup and see any changes you
>> make.
>
>
> If anyone has a proven set of OMAPI commands (shell script, whatever) for
> setting a reserved lease, I'd love to see it.  I've never been able to
> make
> it work in my environment :-(

As an alternative you can just set a really long lease time, like a year
or two. You can do this with a host statement for the particular systems
and put a group around it. Something like

group {
  # 365 days
  min-lease-time 31536000;
  host foo {
    hardware ethernet ..... ;
  }
  host bar {
    hardware ethernet .... ;
  }
}

Note that any system that is online renews it's lease typically half way
through the lease, so systems that are online will always have a current
lease and the ip address won't be given away to another system.

regards,
-glenn