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DHCP allocating extra addresses

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  • DHCP allocating extra addresses

    Our network was recently allocated extra range in the subnet ie: went from 255.255.255.0 to 255.255.254.0. The server was moved to this and all went fine.

    I deleted the existing DHCP scope and set up the new one - from xxx.xxx.xxx.50 to 250.
    I couldn't adjust the subnet distribution - it was greyed out and set to xxx.xxx.254.0.

    Now I'm seeing alerts in the logs - 35 addresses to go.

    Will the server just switch over to handing out the new addresses? Will they be visible in the Leases tab? What will they look like since the addresses there don't show the subnet anyway? I'm sorry to appear confused because - I am!

    Thanks for your time.

  • #2
    Re: DHCP allocating extra addresses

    Hi,
    I deleted the existing DHCP scope and set up the new one - from xxx.xxx.xxx.50 to 250.
    You've created a DHCP scope with 200 valid address to distribute. If you only have 35 left free that means you've assigned 165 already.

    Your newly assigned subnet range should give you enough addresses for 510 hosts.
    Is the third octet an even number? If so you could create a scope to assign addresses in the xxx.xxx.xxx.50 to xxx.xxx.xxx+1.254 range. Instead of what you have.
    If it is an odd number then create a scope to assign addresses in the xxx.xxx.xxx-1.50 to xxx.xxx.xxx.254 range. Replacing what you have.

    You may also want to change the 50 to a 60 or a 75 to allow for more fixed IPs.

    CIDR and Windows DHCP scopes might help clear your confusion some.
    I don't know anything about (you or your) computers.
    Research/test for yourself when listening to free advice.

    Comment


    • #3
      Re: DHCP allocating extra addresses

      [QUOTE=Maebe;79133]Hi,

      You've created a DHCP scope with 200 valid address to distribute. If you only have 35 left free that means you've assigned 165 already.

      Your newly assigned subnet range should give you enough addresses for 510 hosts.
      Is the third octet an even number? If so you could create a scope to assign addresses in the xxx.xxx.xxx.50 to xxx.xxx.xxx+1.254 range. Instead of what you have.
      If it is an odd number then create a scope to assign addresses in the xxx.xxx.xxx-1.50 to xxx.xxx.xxx.254 range. Replacing what you have.

      Thanks so much for your reply. Much appreciated. I think I have it! Soooo - just to be clear: if the original IP setting was : 10.15.60.50 - to 10.15.60.250, with the subnet 255.255.255.0; then the new range could be : 10.15.61.50 - 10.15.61.250, with the subnet 255.255.254.0 (of course your suggestion of extra exclusions for static IP's is very sound and will be taken up) Does this sound right?

      Comment


      • #4
        Re: DHCP allocating extra addresses

        Nope.

        then the new range could be : 10.15.61.50 - 10.15.61.250, with the subnet 255.255.254.0
        This would once again give only 200 addresses.
        Try: 10.15.60.50 - 10.15.61.250, with the subnet 255.255.254.0
        This will give 456 or there abouts addresses.

        A guide on subnetting (an ok guide, CIDR=Classless not classful as it claims). No matter what, to understand IP addressing, you'll have to do some binary. There is no way around it if you wish to understand what is going on.
        I don't know anything about (you or your) computers.
        Research/test for yourself when listening to free advice.

        Comment

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