DHCP & PXE boot workstations

[Eustace, Glen]

We always get two leases for our student lab PCs running Windows, but
PXE booting.  It is caused by the presense or lack thereof of the DHCP
Client Id.  From memory, PXE does not include it so the MAC address is
used - Lease #1, Windows puts the MAC address into the Client Id and
that results in Lease #2.

We have ended up making a class and changing the lease expiry to 10 secs
to try to prevent lease exhaustion in the lab subnets.

We have also seen similar behaviour with Mac's in a lab netbooting and
then booting from their local HDD.

This behaviour has been a royal PIA, but without hacking the code, we
haven't seen a way to avoid it.

Glen.
-- 
Glen Eustace, Infrastructure Development Engineer,
Information Technology Service, Massey University
Ph: +64 6 356099 x 81005, Mob: +64 27 4500321