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Running out of DHCP assigned addresses

Posted on 2012-04-12
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Last Modified: 2012-04-18
Within the last few days, I have been running out of addresses on my DHCP server.  

We have a small school network running on Server 2003.  I have had a pool of addresses available for DHCP assignment: 10.0.0.100 - 10.0.0.254.  The addresses below that are reserved for static IP addresses.  Just this week, I have been running out of IP addresses several times a day.  I have expanded the pool to start at 10.0.0.80 but within a day, those addresses were taken.  I shortened the lease time to 3 days - hoping to free up unused addresses but that does not seem to work.

I do not have a secondary DHCP server set up.  

Any suggestions why this could suddenly be happening and suggestions for fixing it?  

Ken
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Question by:mrken46
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LVL 21

Assisted Solution

by:RK
RK earned 125 total points
ID: 37838109
Hi,

Create a new Scope with having more IP address and Activate this with AD, please don't make the lease period as 3 days. Bydefault this is 8 days. Since you have a small network then you can give the lease period more than that.
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ThorinO earned 175 total points
ID: 37838114
If the addresses are being taken by legitimate machines then you will probably need to expand your subnet. For example if you are currently 10.10.0.0/24 you could update it to be 10.10.0.0/24 which would allow you to use 10.10.1.0 as well and give you another 254 IPs to assign. When you do this would would need to update netmask addresses to be 255.255.254.0 in DHCP or where statically assigned.
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by:Kyle Abrahams
Kyle Abrahams earned 100 total points
ID: 37838137
Have you recently added a wireless network or anything?  Do you have that many machines?

If so expanding the pool is the way to go, otherwise you need to figure out what devices are pulling those IPs.
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Author Comment

by:mrken46
ID: 37838340
ged325,
We have recently reconfigured our WAPs and this began right after that.  The previous IT person had DHCP enabled on the WAPS.  

We have about 50 hard wired PCs and about 25 wireless devices, however, I see many of the wireless devices have multiple IPs assigned to them.

Sounds like I need to both expand my pool and set up a secondary DHCP.
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Assisted Solution

by:JonahJJB
JonahJJB earned 100 total points
ID: 37857063
if your seeing the wireless devices with multiple ip's are they also hard wired?

is your wireless open or secure? If its open you may have random wireless devices pulling ip's.
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by:mrken46
ID: 37862417
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