dissecting DHCP - Q1

[Defryn, Guy]

Hi everyone,

We are reviewing all our infrastructure as part of  DR exercise.
DHCP is high on the list. I want to understand how DHCP really works so
I can advice appropriately. I have set up a lab environment so I can figure out
how DHCP really works. We have no DHCP gurus here as most of us are generalists
so please forgive the stupid questions I might ask.

My first question is regarding the use of the release/renew command
This is how the lease looks like currently

Lease 130.123.128.104
   starts 1 2009/0316 01:28:40;
   ends 1 2009/0316 01:58:40;
   tstp 1 2009/03/23 01:43:40;
   binding state active;
   next binding state expired;
   hardware Ethernet 00:50:56:97:68:46;
   uid "\001\000PV\227hF";
   set ddns-rev-name ="104.128.123.130.in-addr.arpa.";
   set ddns-txt ="317dsfre7j19d04808e3cb85cdb99";
   set ddns-fwd-name = "xp1.mydomain.co.nz";
   client-hostname "xp1"


When I do a release/renew my IP changes to the next available one, in this case 130.123.128.105.
The binding state of previous release gets set to release and next binding state is set to free.

My question here is whether it is normal that it uses the next available in pool.
Is there a reason why it does not re-use same IP address or start at the bottom of the pool again.
The first 3 IPs in my pool are free and I wonder why they did not get used again.
is this all by design?

Cheers


Guy Defryn
Infrastructure Development Engineer
Information Technology Services
Massey University

Address: P.O. Bag 11 222, Palmerston North, New Zealand
Telephone: +64-6-3505799
Web: http://www.massey.ac.nz/

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