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Server2008R2 DHCP Server loses reservations

Posted on 2011-03-23
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Last Modified: 2012-06-27
We have a windows network with about 120 nodes.  We just upgraded the DC to Server 2008R2.  This server also hosts DHCP and DNS (IPV4).  We configured the DHCP white list on this server.

The problem is that I have two clients that keep losing their IP address, a laptop (running XP SP3) and an HP color printer.  The address is obtain by a DHCP reservation from the new 2008R2 DC.  The way that I found that fixes this is to open DHCP in MMC, go to DHCP/Server/Scope, right click on scope, left click on reconcile.  When the reconcile window opens, and I click on verify, the IP address in question appears and I click reconcile (I think).  Sometimes I have to do this twice, but after that, the client is able to obtain an IP address.

I have many clients that obtain their IP address from this server with and without reservations, and it seems that only these two clients are having problems.

Does anyone know a way to fix this?  
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Question by:Stolzman
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Navdeep earned 500 total points
ID: 35200983
Hi,

if you re-create a reservation and reserve the IP do you still face that kind of issue
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Expert Comment

by:uescomp
ID: 35201167
I had a similar problem when I first set up a 2008 R2 DHCP server.  On the old 2003 server the reservations addresses could be outside of the DHCP scope, but 2008 wouldn't allow this.  Once I changed the scope to include the reserved IP addresses the issue went away.
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by:Stolzman
ID: 35201614
Hi, I just deleted the reservation this morning and I am going to try to see if it fails without having a reservation.  

The way the scope is set up now, the address pool is 192.168.42.1-192.168.42.254 with an exclusion range of 192.168.42.128-192.168.42.254, which is for reserved addresses.  Let me know if you have suggestions to improve on this arrangement

Sometimes things work for several days without failing, so I will have to observe this for a week or so to see if these changes are effective.
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Expert Comment

by:elawad
ID: 35223686
allow me to say that your not doing the configuration in the correct way, you can not exclude a range from your DHCP server for the purpose of reservation. if you exclude a range from your DHCP you have to assign the ip addresses excluded to servers or PCs manually i mean you have to put them as static ips where as if you want your DHCP to always assign a certain ip address for a certain computer you have first to have that ip address within your DHCP scope and then reserve the ip to that particular pc using the mac address of taht pc. in this way your DHCP will always assign the same ip address to your computer without an error.
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by:Stolzman
ID: 35235668
I have been configuring my scope pulling reservations from the exclusion range since Server 2000 and has worked.  However, I will delete the exclusion range and see if this helps.  Thanks for your suggestion.
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by:Stolzman
ID: 35235975
Actually, doing some more research, I saw this:  http://technet.microsoft.com/en-us/library/cc782789%28WS.10%29.aspx

You can create reservations using any IP address in the scope's address range, even if the IP address is also within an exclusion range.

So I have reenabled the exclusion range, as I do not think this is the problem.  I continue to recreate addresses that fail, so we shall see if this fixes the problem.
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Expert Comment

by:elawad
ID: 35238319
why dont you gove it a try and try to include the ip addresses you want to reserver in your distgribution address scope and see if that works.
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by:Stolzman
ID: 35243015
good suggestion.  I thought about that, but would rather not have dynamic addresses in my exclusion range.  All the addresses at .128 and above are reservations or fixed.  

I am currently deleteing and recreating reservations that fail, and so far it seems to be working.  If this solution doesn't work, your idea is the next thing I will try.
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Author Closing Comment

by:Stolzman
ID: 35387792
It seems that deleting and recreating the offending reservations has solved the problem.  Thanks!
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