DHCP server policy

Glenn Satchell Glenn.Satchell at uniq.com.au
Thu Jun 8 16:33:37 UTC 2006

>Subject: DHCP server policy
>Date: Thu, 8 Jun 2006 19:16:44 +0300
>From: "Mirkin Michael-MMIRKIN1" <MichaelMirkin at motorola.com>
>To: <dhcp-users at isc.org>
>Do you know how DHCP server select IP address for a client?
>Does it work like FIFO, LIFO, round robbing or randomly?
>I need to enforce DHCP server to select IP address for a client as
>random function
>of client's MAC address. Does it possible with ISC DHCP server?
>        Michael Mirkin
The server will initially allocate addresses starting at the highest
address in the range and working down.

Once a client has been allocated an address the server remembers this
and will allocate the same address next time the client requests it, if
it is still available.

The key for this is the client identifier. If this is not set in the
client request then the mac address is used. Typically only Windows
dhcp clients set the client identifier.

This is only a problem where, for example the same client can boot
multipl eoperating systems, or perhaps PXE or similar. If it uses a
client identifier in one environment but not another then the dhcp
server will think of it as two different clients. There has been quite
a bit of ongoing discussion about whther this is desirable behaviour.

Does this answer your question? If not pehaps you could describe what
problem you are trying to get around.


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