DHCP Issue / Question

[Guest]

Hi, Just hoping someone can answer my question?

I am running server 2000 / 2003 domain controllers (2000 primary domain
controller) with about 200 clients.

DHCP setup on 2000 primary domain controller. 255.255.254.0 Subnet. Client
PC's are assigned addresses fine. Range for distribution is 192.168.13.100 -
192.168.14.240

When i look at the address leases on the DHCP server there is a big gap
between ip addresses ie

192.168.13.100
192.168.13.101
192.168.13.102
192.168.13.103
etc
192.168.13.120
then big gap
192.168.13.150
192.168.13.151
192.168.13.152
etc
192.168.13.190
then big gap
192.168.13.210
192.168.13.211
192.168.13.212
etc
192.168.13.230

when a new client leases ip address dhcp will not use the addresses in the
gap but will use address up around 192.168.13.230

At the end of the day dhcp is working but i was just wondering if it is
normal for it to leave gaps considering most address leases are in order /
straight after one another. And there is also no dns records for the vacant
(gap) ip addresses.

Cheers.

Craig

 

[Paul Bergson [MVP-DS]]

This really has nothing to do with AD, but...

Check the dhcp server to see if you have exclusion ranges defined. If not
check for reservations.
http://technet2.microsoft.com/windo...1204-4ff4-b52c-599c303135d11033.mspx?mfr=true

If you have the dhcp server to check to see if an ip address is in use
before assigned it won't assign addresses either. So do a ping on the
address the dhcp server won't assign, there maybe machines out there using
them and your dhcp server is just avoiding them for conflict reasons.

--
Paul Bergson
MVP - Directory Services
MCT, MCSE, MCSA, Security+, BS CSci
2003, 2000 (Early Achiever), NT

http://www.pbbergs.com

Please no e-mails, any questions should be posted in the NewsGroup
This posting is provided "AS IS" with no warranties, and confers no rights.

 

[Stephen Becker]

That doesn't sound like a problem at all; unless your sever is set to never
expire DHCP leases (3 to 7 days is a better option). DHCP will attempt to
assign the same IP address to a given MAC address each time. My
understanding of MS DHCP is that it will "avoid" reusing an IP address even
after the lease has expired. It will reassign those addresses if it runs
out of other options, but it will prefer to give out addresses it has never
used before.



If you really want to make sure it is working correctly, you can create an
exception range which consumes all of the currently unused high addresses
(so it has no choice but to reuse addresses in the gaps). Then connect a
new interface (new computer) to the network and see what address it gets.
If it pulls an address out of the gap then you should be fine.