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DCHP Scope Full

I have a domain integrated DHCP server on a Windows Server 2012 machine.  The DHCP Server event log is showing warnings of the scope being 93 percent full with only 9 ip addresses available.  The DHCP server is not handing out new ip address, but when I look in the GUI of the management console I count more than 70 unused IP addresses in the scope.
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matthewi
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matthewi
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MikeIT ManagerCommented:
Do you have the DHCP role installed on any other server that may have taken over authoritative role?
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matthewiAuthor Commented:
I do have a second server that's configured for DHCP failover.  When I right-click the DHCP server in the gui of my primary DHCP server OR my backup server, I only have the option to "unauthorize"; which leads me to believe it is authorized.
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matthewiAuthor Commented:
If I look at the DHCP statistics, it shows 135 addresses in use.  I count all the addresses in use and it's not even half that.
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QlemoBatchelor, Developer and EE Topic AdvisorCommented:
Ranges might be excluded, and/or addresses reserved.
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Natty GregIn Theory (IT)Commented:
everything that does not need static make sure their leases expire to free up ip addresses
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matthewiAuthor Commented:
No it's not that.
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matthewiAuthor Commented:
How do I "make sure their lease expires"?  All are set to expire after 1 day.
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Will SzymkowskiSenior Solution ArchitectCommented:
You need to look at your reservations for your scope and also look at if you have any scope Exclusions. Any of these could be creating this issue.

Will.
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matthewiAuthor Commented:
i have a /32 scope with 110 ip addresses excluded and about 50 reservations.  That leaves over 190 addresses in the pool to hand out.  Less than half of those are assigned.
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MikeIT ManagerCommented:
A /32 scope gives you 1 usable IP address...
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matthewiAuthor Commented:
/24 sorry
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Will SzymkowskiSenior Solution ArchitectCommented:
/32? How do you get 190 addresses from that? that only give you 2 host broadcast IP and Network ID. I think you are mistaken something for something else. Also do you have multiple machines that are connected via wireless and ethernet? also taking into account for tablets and phones as well?

Subnet Cheat sheet
http://www.aelius.com/njh/subnet_sheet.html

Will.
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MikeIT ManagerCommented:
/24 scope with 160 addresses not usable only leaves ~90 usable addresses.

From your post before it sounds like you are out of addresses, because half of 190=95
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Will SzymkowskiSenior Solution ArchitectCommented:
/24 = 256 - 2 (broadcast and network id) 254 possible hosts.

254-110-50 = 94

So after that you have 94 usable addresses which DHCP will hand out.

Will.
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MikeIT ManagerCommented:
94 is approx. 90 lol
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matthewiAuthor Commented:
I was not very clear and made some mistakes in my previous posts.  I have an exclusion range of about 110 IP addresses BUT the reservations I have which is about 50-60 are INSIDE that exclusion range which leaves me with around 150 in the DHCP pool with about 80 used and 70 free.
I.E.
Pool 192.168.1.0
Exclusion Range 192.168.1.1-192.168.1.110
Reservations with Exclusion Range
Out of the leftover range, 192.168.1.111-192.168.1.254, only 80 addresses are assigned.  For instance, the address 192.168.1.202 is not assigned to anything.  There are 70 others like this that are not assigned, not in the exclusion range, not reserved, and in the pool of available addresses.
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Will SzymkowskiSenior Solution ArchitectCommented:
If the above is the case then the only thing i can think of is the following...
- DHCP server has been unauthorized
- DHCP server stopped or needs to be restarted
- New network configuration LAN's added to the network without add the IP Helper to the switch with the new VLAN

Aside from that it should be handing out DHCP addresses if the above do not apply.

I would also check the logs as well to see if there are any errors specifically related to DHCP.

Will.
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matthewiAuthor Commented:
Will,

DHCP server is authorized.
DHCP server has been restarted as well as entire machine just in case.
The only network configuration changes that have been made were changing the default gateway router from having static routes to using EIGRP.  But I don't believe that would affect anything since client broadcasts can reach the DHCP server with or without the default gateway.
The only errors I saw relating to DHCP in the DHCP Server section of the event log had to do with the DHCP pool being nearly depleted.
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matthewiAuthor Commented:
Update:
If I set a reservation for a client using one of the unused ip addresses, the client picks up the IP address right away. Otherwise, the clients get no ip.
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QlemoBatchelor, Developer and EE Topic AdvisorCommented:
Since noone has more ideas for troubleshooting, my next step would be to capture the network traffic of this client for BOOTP/DHCP, to see what part of the negotiations fails.
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QlemoBatchelor, Developer and EE Topic AdvisorCommented:
Is there a solution? Otherwise this question should rather be deleted than accepting my (generic) advice.
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