DHCP code in 2.0.4+

[A.L.M.Buxey at lboro.ac.uk]

Hi,

> When we tried it back in 2007 with an Active/Active configuration, the 
> two instances of ISC DHCPD started handing out duplicate leases 
> completely arbitrarily. We scrapped the second instance and went down to 
> a single one. Haven't tried it again since.
>
> It didn't work then... it may do now.

we run in an active/standby home-made configuration. the lease file
is copied periodically from the live server to the standby (heck, we may lose
some details if there is a problem but each lease file revision is logged)
and then a process on the standby checks whether dhcpd is alive on the master.
if it isnt, is starts dhcpd process ..if it detects the master is alive again
it kills its process. 

why? when we tried any of the active/active and stanbdy methods in ISC DHCPD
at the time it b0rked in many weird ways. this works.  havent had time to
get the 4.1.x runway time yet...been really waiting to get around to FR DHCP :-)

alan