dhcp server

Posted on 2007-03-29
Medium Priority
Last Modified: 2010-03-05
On my domain server under DHCP the server has a yellow warning sign on the server itself what does this mean?
Question by:scripttron75
LVL 78

Expert Comment

by:Rob Williams
ID: 18820842
Usually this means that 90% or more of your DHCP lease are in use. You need to increase the size of the DHCP scope.
LVL 14

Expert Comment

ID: 18820877
Agreed with Rob. If you right click on teh scope and select display statistics it will tell you how many free addresses you have left.

Author Comment

ID: 18824934
it looks like i have 0 free, how do i expand to another scope we have too scopes on 2 different domain controllers the first one is to and the second is to, the rest are used for network components.  
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LVL 78

Accepted Solution

Rob Williams earned 252 total points
ID: 18828912
It could be a big project. You will need some time, and plan it out carefully. I assume you currently are using a subnet mask of ??
If that is the case, your subnet includes usable IP's of - which is completely used up. Changing the subnet mask to would double the size of your subnet; -
However, it's not as simple as that. Assuming both scopes are almost used up and you want to split the IP's evenly, you will likely want to do something like;
DC1 - and DC2 -
In order to do so all DHCP leases will have to be renewed and their is the concern DC2 could hand out an IP in the to  range, to a device with an existing IP. Also all client machines will require the updated subnet masks. You could change your DHCP lease time to 8 hours, wait till all existing leases have expired, and on the next Friday night make the changes, so they will propagate over the weekend and Monday morning as users boot up downed machines.
Don't forget to make changes to all devices such as servers, routers, and printers with static addresses.
To further reduce the chance of conflict you could make a bigger scope and not reuse the current DHCP scopes. Perhaps save 10.1.1.x for static IP's. To do that, you could choose a subnet mask of (this will x4 the size of current subnet i.e. -, and configure something like:
DC1 - and DC2 -


Assisted Solution

drmarston earned 248 total points
ID: 18838418
Totally agree with RobWill that this needs to be thought out.
Since it looks like you might be doing an overhaul of your addressing space, NOW is the time to look at a number of other things when thinking this through;
1) Growth potential ; how many workstations / network devices will be added in the near future??
2) branch offices / Wan connections / cross domain trusts?
3) V-lans and broadcast domains??
4) Physical segmentation?

I'm not trying to complicate the issue, Robs comment is right on target, I'm just saying that this is the perfect opportunity to take 2 steps back and look at the BIG picture of your network and plan accordingly.



Expert Comment

ID: 19233604
RobWill should get the points, He awnsered the question, I just added a suggestion.
LVL 78

Expert Comment

by:Rob Williams
ID: 19233622
Glad to share the points drmarston, if awarded, however thank you for the offer.
Cheers !

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