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Windows DHCP Server -- over 256 addresses ?

Posted on 2015-01-10
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Last Modified: 2015-01-28
I will be running out of IPV4 addresses
in a few months, even after setting WIFI
devices to "release unused addresses faster"

What are the recommended steps
to get over 256 addresses without
having to do separate VLANs or manually
changing subnet mask on my static IP
machines ?
--------------------------------------------------------

Details

  ** One Domain

  ** Three Locations
        ** one Windows 2003 DC at each location,
           upgrading to 2012 in 60+ days
              ** 192.168.24.x
              ** 192.168.25.x
              ** 192.168.26.x

  ** Subnet Mask --> 254 usable IPs
        ** 255.255.255.0

  ** Networks --> using dynamic DHCP IPs
        ** HardWired
              ** Employee PC & VOIP
                 phone using the same cable
        ** Wireless
              ** Employee
              ** Guest

--------------------------------------------------------

POSSIBLE OPTIONS

 1. change subnet mask to 255.255.0.0
    (Class B block) to use all 65,536
    addresses, which extends existing scope

 2. add a new address range scope
    (for example 192.168.1.x)
    to DHCP server

 3. superscope

 4. etc ?
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Question by:finance_teacher
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8 Comments
 
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Accepted Solution

by:
Will Szymkowski earned 250 total points
ID: 40542144
You can do this a couple of ways. All depends on what you want to do.
First Method
- create a new address range only for Wifi devices. This will help to easily identify wireless devices just by looking at the IP. It will also save up IP's for your wierd devices.

Second Method
- modify the subnet mask to 255.255.254.0 This will double your address range and give you 510 usable addresses for your environment. Or you could even do 255.255.253.0 and this address range will provide 1022 usable licenses.

Whatever way you do it is your choice. Both options have their benefits. You could even implement both so that you get the wireless on its over range.

Will.
0
 

Author Comment

by:finance_teacher
ID: 40542175
Currently my IPs are "192.168.24.1 to 192.168.24.255" for ONE location when using 255.255.255.0

Would my IPs be "192.168.24.1 to 192.168.24.500" for ONE location when using 255.255.254.0 ?
If not, what would the IPs be ?
0
 
LVL 53

Expert Comment

by:Will Szymkowski
ID: 40542182
No you cannot go over 255 in a single octet. It would look like this...

IP Range for 255.255.254.0
192.168.24.1 - 192.168.25.254

Will.
0
 
LVL 25

Assisted Solution

by:Fred Marshall
Fred Marshall earned 125 total points
ID: 40542452
Also, I would avoid the use of "classes" and go with Will Symkoski's advice.
Doubling is much more likely to work than going to some huge number of addresses in the range.

And, you should make sure that the DHCP server, whatever that device may be, is capable of accepting a range outside of 255.255.255.0 or /24.  Some will and some won't.  Some commodity routers will only do /24 which is what you have for a range now.
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LVL 53

Assisted Solution

by:Will Szymkowski
Will Szymkowski earned 250 total points
ID: 40542574
Unless you have a high-end router you will get very limited options for DHCP. I would personally just use the Windows DHCP service which has a lot of flexibiliy for different options and services.

Will.
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Assisted Solution

by:Qlemo
Qlemo earned 125 total points
ID: 40542996
If the locations need to communicate with each other, you'll have to make sure the networks do not overlap. I would change e.g. to 16, 20, 24, leaving 1022 addresses for each location.
0
 

Author Comment

by:finance_teacher
ID: 40545833
All of my Domain Controllers are also doing DHCP
at each site, which replicate AD between sites.

Can I have a /23 255.255.254.0 on my one BIG location and keep
/24 255.255.255.0 at my TWO smaller locations if the /23 does not
overlap the other locations' IPs ?

  ** http://www.aelius.com/njh/subnet_sheet.html
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Expert Comment

by:Qlemo
ID: 40546149
Yes, of course.
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