DHCP, scope problem

I have set up a DHCP server with the range of to on a class C, also I have excluded to  The server has been assigning IP numbers just fine until it reached 80 and then it skipped to 178.  It is now up to 246 and i'm not sure what will happen when it hits 254.  Can someone tell me if this is a problem and what I might do to fix it?
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gaucigConnect With a Mentor Commented:
This is a Known Problem from Microsoft see bellow....

PRB: DHCP Skips Addresses If Exclusion Range Included in Scope

Last reviewed: April 4, 1997
Article ID: Q140989 The information in this article applies to:

•Microsoft Windows NT Server versions 3.5 and 3.51 •Microsoft Windows NT Server version 4.0


When you use an exclusion range with DHCP, addresses offered to clients may not begin at the first address in the scope.


This behavior is by design.


Leases offered to clients from a DHCP scope will be offered consecutively, starting with the first address in the IP address pool. But if an exclusion range is added to the scope, the first lease offered may not be the first address in the IP address pool.

For example, if a scope is created using a starting address of and an ending address of, the first lease address offered to clients will be

Alternatively, if an exclusion range of to is added to the scope, the first lease address offered will be Leases will be offered consecutively through, skipping the excluded range. After, the next leases offered will be through consecutively.

This may also occur when multiple ranges of addresses are included in the DHCP scope.
What Services pack / NT Version are you running ?
nealAuthor Commented:
It's NT 4.0 and I have not installed any service packs yet...
I had SP1 installed but had to switch servers and never have reinstalled, I was also leary of SP2 and havn't touched it either.

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I'd recommend sp2 at least. It contains a lot of DHCP
fixes including dealing with bad addresses.

The question is , even when it jumps to 178 does the number of available addresses tally. (ie. the range less your exclusions)..?

It should start at the lowest possible address and give the first available address it can find. The jump you described seems odd, and may be fixed by one of the S'packs. If it gets to 254 , it will scan the whole range for an available address , not just the next few in the range.
Eric BCommented:
Go into dhcp config and check available addresses left. That will tell you if the skip is random or if it skipped for a reason.
What mask are you using?
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