Best practice for defining static IP addresses?

[Simon Hobson]

Shawn Holland wrote:

>When I exclude that 10.250.15.2 from the pool, remove the host entry,
>restart dhcpd. When the client tries to do a DHCPREQUEST the following
>happens:
>
>dhcpd: DHCPREQUEST for 10.250.15.2 from 00:1b:9e:8a:71:1a via eth0:
>unknown lease 10.250.15.2.
>
>I would like to be able to have it just send a DHCPNAK to help the
>client do a DHCPDISCOVER faster. Right now it does do a DISCOVER but it
>takes several attempts of doing a REQUEST and (I'm sure its a windows
>vista issue) it doesn't always DHCPDISCOVER. But if that DHCPNAK could
>be sent it would be very helpful.

What you see is normal - the client already has a valid lease AND it 
has determined that it's on the same network (checks the MAC address 
of the router). In this situation, the client can continue to use 
it's existing lease.

The DHCP server doesn't NACK the requests because the address is 
valid for the subnet even though it is not defined. You can get it to 
NACK the address by explicitly defining it as not available :

pool {
   range a.b.c.d ;
   deny booting ;
}

The server MUST also be authoritative.