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  • DHCP Superscope shows wrong IP

    I just tried to create a DHCP scope that would encompass 192.168.7.1 through 192.168.8.254 255.255.254.0

    Windows prompts me that it can't make it one scope, do I want to create a superscope? I click on yes and yada, yada, yada everything looks fine except the first scope 7.1-7.254 is actually named Scope[192.168.6.0]

    why would it pull the 6.0? The actual address pool is correct (7.0)
    Thank you,

    Marc

  • #2
    Re: DHCP Superscope shows wrong IP

    The following subnets are valid

    192.168.0.0 - 192.168.1.255
    192.168.2.0 - 192.168.3.255
    192.168.4.0 - 192.168.5.255
    192.168.6.0 - 192.168.7.255
    192.168.8.0 - 192.168.9.255
    etc.

    So you're subnet is invalid.
    Microsoft does it correct by choosing the subnet where 192.168.7.x belongs to.
    Marcel
    Technical Consultant
    Netherlands
    http://www.phetios.com
    http://blog.nessus.nl

    MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
    "No matter how secure, there is always the human factor."

    "Enjoy life today, tomorrow may never come."
    "If you're going through hell, keep going. ~Winston Churchill"

    Comment


    • #3
      Re: DHCP Superscope shows wrong IP

      192.168. 0000 0111 . 0000 0001
      192.168. 0000 1000 . 1111 1110
      255.255. 1111 1110 . 0000 0000 (1=network ID, 0=Host ID)

      So - the first address is in network
      192.168. 0000 0110 . 0000 0000 (= 192.168.6.0/23)

      and the second address is in network
      192.168. 0000 1000 . 0000 0000 (= 192.168.8.0/23)

      They are in completely different networks. To put them in the same network (and therefore in a single scope) you need less bits as subnet mask. In fact you need 3 bits less:
      192.168. 0000 0111 . 0000 0001
      192.168. 0000 1000 . 1111 1110
      255.255. 1111 0000 . 0000 0000

      Now, the first address is in network
      192.168. 0000 0000 . 0000 0000 (=192.168.0.0)

      and so is the second address. Supernetting gets around the problem but it looks messy in DHCP.


      Tom
      For my own and your protection, I do not provide support by private message under any circumstances. All such messages will be deleted and ignored.

      Anything you say will be misquoted and used against you

      Comment


      • #4
        Re: DHCP Superscope shows wrong IP

        ...so if I wanted the network 192.168.200.0/22 wouldn't the end IP be 192.168.204.255?

        This should give me 1022 addresses correct? I assume I am not since when I try to put it in my DHCP server it again creates a super scope w/ 2 scopes, the 200 and the 204.

        Never mind...I just figured out that it should end w/ 203.255. to end with 204.255 I need to go to /21.

        ...learning. Reputation points given to all. Thank you.
        Last edited by tnshurtm; 11th December 2007, 20:21.
        Thank you,

        Marc

        Comment


        • #5
          Re: DHCP Superscope shows wrong IP

          Try this
          http://www.subnet-calculator.com/
          Marcel
          Technical Consultant
          Netherlands
          http://www.phetios.com
          http://blog.nessus.nl

          MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
          "No matter how secure, there is always the human factor."

          "Enjoy life today, tomorrow may never come."
          "If you're going through hell, keep going. ~Winston Churchill"

          Comment


          • #6
            Re: DHCP Superscope shows wrong IP

            Thank you,

            Marc

            Comment


            • #7
              Re: DHCP Superscope shows wrong IP

              You're welcome
              However I think it's wise to learn to subnet.
              Marcel
              Technical Consultant
              Netherlands
              http://www.phetios.com
              http://blog.nessus.nl

              MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
              "No matter how secure, there is always the human factor."

              "Enjoy life today, tomorrow may never come."
              "If you're going through hell, keep going. ~Winston Churchill"

              Comment

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