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DHCP address pool

    Question

  • Hi,

    I have a DHCP server handing out addresses from 10.0.1.60 - 10.0.1.250. Our network address is 10.0.0.0 with mask 255.255.253.0. We are running low on addresses and after some investigation we noticed a range that is free (from 10.0.0.101 to 10.0.0.200). As far as I know it is not possible to have two address pool on the same DHCP scope. I know I have two options. I can change the address pool to 10.0.0.101 - 10.0.1.250 and then add an exclusion range or add a second DHCP server and add the new address pool there.

    My questions - which method is better? Is there any advantage in going with one option or the other? Is there another method that would be preferred over the ones I have mentioned?

    Let me know if you need more info. Thanks for reading.

    Qazi

    Wednesday, March 02, 2011 11:49 AM

Answers

All replies

  • Hi

    i am assuming 255.255.253.0 is a typo and that it should actualy be 255.255.252.0 in this case you should have 1022 addresses to give out this so because your network address will be 10.0.0.0 and your broadcast will be 10.0.3.255. So your ip address scope for DHCP is possible from 10.0.0.1 to 10.0.3.254

    now i think you can create a new scope in dhcp. Open DHCP, right click Server_Name  and select new scope. Enter the address range you said is free which is 10.0.0.101 to 10.0.0.200 and the subnet mask 255.255.252.0 and also the other relevant settings for DHCP same as the one in your other scope, activate the new scope as well and i think it should work.

    Please post up if this does not work or if you need any more info and all

                             


    tech-nique
    Wednesday, March 02, 2011 1:03 PM
  • Hi tech-nique,

    Yes, it is a typo but its not 252, its 255.255.254.0 (10.0.0.0 - 10.0.1.255).

    The idea of creating a second scope is not bad though I wouldn't want to test it out on a live environment. can anyone reading this post conform if this will work?

    Qazi

    Wednesday, March 02, 2011 3:15 PM
  • I would just modify the scope and add the exlusion range to accomodate the new IPs.  Not sure what the concern is.  Even if you delete the scope, recreate it, as long as you have Conflict Detection turned on, there will not be an issue with issuing IPs in use.

    With regard to a second DHCP server...its always a good design to have two servers and split the scope 50/50.

    Here is some more information to help you:

    Increasing IP Lease Availability in DHCP
    http://www.anitkb.com/2010/06/increasing-ip-lease-availability-in.html

    Using Conflict Detection in DHCP
    http://www.anitkb.com/2010/03/using-conflict-detection-in-dhcp.html


    Visit: anITKB.com, an IT Knowledge Base.
    • Proposed as answer by Shifu-TandyBrands Wednesday, March 02, 2011 8:10 PM
    • Marked as answer by {r00t} Thursday, March 03, 2011 9:12 AM
    Wednesday, March 02, 2011 4:51 PM
  • Hi Qazi,

     

    Thanks for posting here.

     

    I think it’s depend on you . Both options have their own advantage or disadvantage . For example, with adding new server option , it will improve the availability, however will also  spend more time for server maintaining.

     

    Design Option 1: Split Scopes

    http://technet.microsoft.com/en-us/library/dd296651(WS.10).aspx

     

    DHCP Best Practices

    http://technet.microsoft.com/en-us/library/cc780311(WS.10).aspx

     

    Thanks.

     

    Tiger Li

     

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    • Marked as answer by {r00t} Thursday, March 03, 2011 9:12 AM
    Thursday, March 03, 2011 3:16 AM