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how to find the unused IP's in domain? RRS feed

  • Question

  • Hi Friends,

    Kindly guide me the steps to find the Free IP in network. There are 250-300 computers in domain. They all are using static IP's so Ip management is though. If i used the same IP there is IP conflict error. So kinldy help on this  

    Friday, September 21, 2012 1:09 PM

Answers

  • Actually, this sounds as though Deepak may be in a situation where he is not the final decisionmaker about implementing DHCP, possibly on a "special needs" LAN. Some suggestions:

      •  you should perform the scan at several different times to capture devices which are off/non-responsive/disconnected.
      • Do you truly have 200-300 nodes? If you're using a classic ClassC/24-bit subnet mask - quite likely I suspect since that tends to go with unmanaged IPs - you  only have 254 available addresses. This means you have either few or possibly no available addresses anyway.
      • When you DO have to switch to DHCP, it's going to be a very, very painful week as you switch over address management. Get a TCP/IP expert involved to minimize your grief; depending on LAN config and client Windows versions, you'll have a lot of work, but it's possible to use management scripts to handle much of the migration remotely.

    However, as everyone indicates, you do want to get away from static addressing as rapidly as possible. I spent a few months as part of a team supporting a 170-seat LAN with static IP in the late 1990's, and it was almost impossible to add anything. We were still finding static nodes a year after migration.

    • Marked as answer by Bill_Stewart Monday, September 24, 2012 2:56 PM
    Monday, September 24, 2012 3:15 AM

All replies

  • if you have a domain environment, why are you using fixed ip addresses and not DHCP?

     

    But to answer your question, you need to use an IP Scavenge utility, it will basically perform a ICMP ping to every ip address in a specified range and report back addresses in use, or free.

    These are a few:

    Angry IP

    http://www.angryip.org/w/Home

    IP Scanner

    http://www.radmin.com/products/ipscanner/


    Kriss Milne, MCSE | Infrastructure Specialist


    • Edited by Kriss Milne Friday, September 21, 2012 1:13 PM
    Friday, September 21, 2012 1:13 PM
  • Thanks Kriss. Still now there is no idea to implement DHCP servers. In IP scanner software. how can i find the free Ip's in domain

    because it shows in 3 category i think. Dead,alive,Unknown


    Thanks, Deepak.J 9629106697



    • Edited by Deepak.J Friday, September 21, 2012 1:35 PM nothing
    Friday, September 21, 2012 1:34 PM
  • Hi

    In the IP Scanner application, click view and click show unknown.

    If Alive then a device responded

    If unknown then the application received no response, meaning the IP is probably available unless the device is turned off, or firewall or setting prevents responses to ICMP

    I'm not 100% sure what dead means, but I wouldn't use IP's that are flagged as dead. :)


    Kriss Milne, MCSE | Infrastructure Specialist


    • Edited by Kriss Milne Friday, September 21, 2012 1:46 PM
    Friday, September 21, 2012 1:45 PM
  • Thanks Kriss. Still now there is no idea to implement DHCP servers. In IP scanner software. how can i find the free Ip's in domain

    because it shows in 3 category i think. Dead,alive,Unknown


    Thanks, Deepak.J 9629106697



    You cannot know the answer to this.  Youcan only know if an IP responds.  Servers fo not have to respond to a ping.

    You need to start by learning a bit about IP networking then you would see why your question does not make any sense.

    You should be using DHCP after all this is the 21st century.  You are a century behind the times.  In this century we let computers automate those things that humans are not very good at doing.


    ¯\_(ツ)_/¯

    Friday, September 21, 2012 1:45 PM
  • Here is a simple Powershell IP scanner:

    1..254 | % { if (!(Test-Connection "10.0.0.$_" -Count 1 -Quiet)) {Write-Host "10.0.0.$_"}}


    Grant Ward, a.k.a. Bigteddy


    • Edited by Bigteddy Friday, September 21, 2012 1:50 PM
    Friday, September 21, 2012 1:49 PM
  • There is no concept of "free IPs in a domain." There is "unused IP address on a network," but as pointed out, there's not a way to really tell if an IP is really not being used simply by ping (ICMP echo request), as a device can use an IP address and not respond to ping. IMO it is much more sensible to use DHCP. (Note that if fixed IP addresses are the goal, DHCP can be configured to give out fixed IP addresses using reservations.)

    In any case, this is not a scripting question but rather a network management question.

    Bill

    Friday, September 21, 2012 2:25 PM
  • To add to Bill's excellent arguments I would like to say that I have been lobbying of almost a decade for teh use of DHCP for managing IPs.

    In DHCP you can allocate an IP as a reservation that is tied to teh adpters MAC address. This will then behave exactly like a permanent address.

    In the past WIndows would not let us do this for some applications like an ISA server of SBS.  WIndows versions now allow the use of dynamic reservations.

    In the past we kept track of IP usage via a spredsheet or notes on someones desk blotter.  Today we use DHCP to audit IP usage.

    DHCP is available as an installation option on every version of WIndows Server.  The WS2008 andlater versions are very flexible and easy to use.  Theyare especially good at managing small subnets with limited address space although using private addresses is perferred.


    ¯\_(ツ)_/¯

    Friday, September 21, 2012 2:45 PM
  • Actually, this sounds as though Deepak may be in a situation where he is not the final decisionmaker about implementing DHCP, possibly on a "special needs" LAN. Some suggestions:

      •  you should perform the scan at several different times to capture devices which are off/non-responsive/disconnected.
      • Do you truly have 200-300 nodes? If you're using a classic ClassC/24-bit subnet mask - quite likely I suspect since that tends to go with unmanaged IPs - you  only have 254 available addresses. This means you have either few or possibly no available addresses anyway.
      • When you DO have to switch to DHCP, it's going to be a very, very painful week as you switch over address management. Get a TCP/IP expert involved to minimize your grief; depending on LAN config and client Windows versions, you'll have a lot of work, but it's possible to use management scripts to handle much of the migration remotely.

    However, as everyone indicates, you do want to get away from static addressing as rapidly as possible. I spent a few months as part of a team supporting a 170-seat LAN with static IP in the late 1990's, and it was almost impossible to add anything. We were still finding static nodes a year after migration.

    • Marked as answer by Bill_Stewart Monday, September 24, 2012 2:56 PM
    Monday, September 24, 2012 3:15 AM
  • Alex - I like that.  A "from teh foxholes" response.  Yes = in a large network reolution can take years.  Thsi was, in partm ther ereason that DHCP was invented more thatn three decades ago.  To bad so many are still running on Ataris and driveing a Ford Model-A.

    -


    ¯\_(ツ)_/¯


    • Edited by jrv Monday, September 24, 2012 4:08 AM
    Monday, September 24, 2012 4:08 AM