<div dir="ltr"><div><div><div>Thanks Glenn,<br><br></div>Of course I saw it in the man page but yet I have no clue how to use it and more specifically how it will be useful for us. I think I'll have to experiment with it. So far, what I understand is that an IP will be assigned by dhcpd daemon and the only, and probably good way, to find the IP assigned to a server will be by doing a nslookup on the hostname. Of course if proper integration is done with BIND.<br><br></div>Thanks,<br></div><div>Bernard<br></div><div><div><br><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Feb 25, 2016 at 7:10 PM, Glenn Satchell <span dir="ltr"><<a href="mailto:glenn.satchell@uniq.com.au" target="_blank">glenn.satchell@uniq.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Bernard,<br>
<br>
ISC dhcpd ships with a very comprehensive set of man pages, so I would<br>
suggest perusing these:<br>
<br>
dhcpd.conf, dhcpd, dhcp-options, dhcp-eval<br>
<br>
In this case the reserved leases are mentioned in the dhcpd.conf man page.<br>
I've included the section below in the hope that google will find it for<br>
future searches.<br>
<br>
I would also suggest that you can approximate a reserved lease by setting<br>
the lease time to be very long, say 1 year (31536000 seconds).<br>
<br>
regards,<br>
-glenn<br>
<br>
man dhcpd.conf<br>
...<br>
RESERVED LEASES<br>
It's often useful to allocate a single address to a single<br>
client, in approximate perpetuity. Host statements with<br>
fixed-address clauses exist to a certain extent to serve<br>
this purpose, but because host statements are intended to<br>
approximate 'static configuration', they suffer from not<br>
being referenced in a littany of other Server Services, such<br>
as dynamic DNS, failover, 'on events' and so forth.<br>
<br>
If a standard dynamic lease, as from any range statement, is<br>
marked 'reserved', then the server will only allocate this<br>
lease to the client it is identified by (be that by client<br>
identifier or hardware address).<br>
<br>
In practice, this means that the lease follows the normal<br>
state engine, enters ACTIVE state when the client is bound<br>
to it, expires, or is released, and any events or services<br>
that would normally be supplied during these events are pro-<br>
cessed normally, as with any other dynamic lease. The only<br>
difference is that failover servers treat reserved leases as<br>
special when they enter the FREE or BACKUP states - each<br>
server applies the lease into the state it may allocate from<br>
- and the leases are not placed on the queue for allocation<br>
to other clients. Instead they may only be 'found' by<br>
client identity. The result is that the lease is only<br>
offered to the returning client.<br>
<br>
Care should probably be taken to ensure that the client only<br>
has one lease within a given subnet that it is identified<br>
by.<br>
<br>
Leases may be set 'reserved' either through OMAPI, or<br>
through the 'infinite-is-reserved' configuration option (if<br>
this is applicable to your environment and mixture of<br>
clients).<br>
<br>
It should also be noted that leases marked 'reserved' are<br>
effectively treated the same as leases marked 'bootp'.<br>
<div class="HOEnZb"><div class="h5"><br>
On Fri, February 26, 2016 2:26 am, Bernard Fay wrote:<br>
> I have to find out about this "reserved" thing. I don't understand it.<br>
> Google, please, help me!<br>
><br>
><br>
> On Wed, Feb 24, 2016 at 1:44 PM, Chuck Anderson <<a href="mailto:cra@wpi.edu">cra@wpi.edu</a>> wrote:<br>
><br>
>> On Wed, Feb 24, 2016 at 01:17:13PM -0500, Bernard Fay wrote:<br>
>> > When the dhcpd server assign a static IP to a device, it also instruct<br>
>> bind<br>
>> > to add an entry in the DNS zone file. One thing I realized is that if<br>
>> a<br>
>> > device didn't renew his lease, the entry in the DNS zone file is not<br>
>> > removed. I would have thought to use the zone files to know if a<br>
>> device<br>
>> is<br>
>> > in use or not. I had in mind that the lease time would have help to<br>
>> know<br>
>> > if a device therefore an IP is use or not. In other words, a device<br>
>> > requires an IP and the dhcpd server assigned it a statically defined<br>
>> IP<br>
>> > address. The dhcpd server also instruct bind to add an entry in the<br>
>> > appropriate zone file. Eventually the device is turned off, the lease<br>
>> time<br>
>> > reach its limit then I would have expected the dhcpd server to<br>
>> instruct<br>
>> > bind to remove the entry regarding this device but it is not the case.<br>
>> > Then I could have take a look at the zone files to know what is in<br>
>> used<br>
>> and<br>
>> > I would know what is not in use.<br>
>> ><br>
>> > Either I made something in my configuration or I was expecting too<br>
>> much<br>
>> > from dhcpd and bind.<br>
>><br>
>> You can do that, but you have to use "reserved" leases rather than<br>
>> fixed-address statements. ISC dhcpd doesn't track the expiry of<br>
>> fixed-address leases.<br>
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