I have the same IP Address showing up for different computers

Posted on 2006-04-01
Last Modified: 2008-01-09
Hello, I went to my Main Server-Administrative Tools-DNS-Domain name to see the ipaddresses.  I noticed that some IPAddresses were showing for different users.  I want IPAddress especially that is showing one computer in conflict with another.  What would happen if I delete the IPAddress/computer from this location that I don't want.

Is it ok to have IPAddresses showing for different users at the same time in this location?  Thanks.\

Question by:Mahonek
    LVL 77

    Accepted Solution

    All IP addresses should only be associated with a single computer. It is possible due to changes that some have not been deleted from DNS. You can manually delete them but you should also verify that your system is configured to Dynamically (automatically) update your DNS records.
    A Windows server should be the DHCP server rather than a router. If so open the DHCP management console, expand the server name, and right click on the scope and choose properties. Under the DNS tab verify the following are enabled:
      -Enable DNS dynamic updates
      -Always dynamically update DNS A and PTR records
      -Discard A and PTR records when lease is deleted
    Also on your workstations you should enable "Register this connection's address in DNS" under DNS in the advanced TCP/IP properties of your network adapter.
    LVL 1

    Expert Comment

    In theory it is OK until you are trying to access a device using a hostname and can't because the IP address on your dns is wrong. Have a look at ipconfig /flushdns and /registerdns as an easy way to make sure a machine has the right IP address listed.
    LVL 4

    Expert Comment

    Are you looking at the Reverse dns records?  I noticed the focus of your question seems to be the IP Addresses.  (the reverse records show the IP in the left column, the machine in the right column, however the standard records show the MACHINE name in the left column and the IP ADDRESS in the right column)

    IF you ARE looking at the reverse records, the yes, it IS ok to see a machine associated with multiple addresses.  When a machine receives a new DHCP lease, it will contact the DNS server and add a new record, BUT the old one will NOT be removed.  It will remain as originally written untill a new machine leases that IP address and then overwrites the old information with new information...

    All of that said you may want to enable scavenging of stale DNS records.  Microsoft DNS servers 2000 and newer support that feature and will clean up the many records created by the machines that automatically update DNS.
    LVL 77

    Expert Comment

    by:Rob Williams
    Thanks Mahonek,

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