having IP conflicts

[Sherman Smith]

I'm on a domain with 3 scopes and one subnet. The scopes
are 10.100.39.x, 10.100.139.x, 10.100.239.x and the subnet
mask is 255.255.255.0. There are about 300 client machines
on this domain. 39.x and 139.x scopes has a rang from 30 -
245. The 239.x scope has a range of 120-245 . The problem
I'm having is that I keep getting IP conflicts pretty much
on a daily basis and DHCP assign very few addresses from
the 139.x scope and no addresses from the 239.x scope.
Could anyone tell me why I keep getting IP conflicts and
why DHCP doesn't assign any addresses from the 239.x scope?

 

[Dusty Harper {MS}]

The subnet mask is wrong if you are on a single subnet. The subnet mask
would need to be 255.255.0.0. DHCP is a pretty dumb service. It will hand
out leases by looking at the GIAddr field in the DHCP packet ( This allows
it to determine the scope to use ). This field is only populated though if
the DHCP Discover is sent over a router that Relays the packet. Otherwise
DHCP will use the scope that corresponds to the subnet that the interface is
part of.