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DHCP Address Leases List shows hosts with static IP addresses

    Question

  • Hello,

    I am working with Windows Server 2008 x64 and about 50 Windows 7 clients. On the server I have the DHCP role installed with a scope size of 17 from xxx.xxx.xxx.43 - 59. I have an average of 5 computers that should be obtaining an address through DHCP and the rest of the computers have a static IP set. My problem is that some computers are still grabbing an address from the DHCP server even though they have been assigned a static IP address. The Address Leases list on the server shows an average of 14 IP addresses taken. I have verified the computers on the list have been assigned a static IP.

     

    Why are these few clients still showing up on the Address Leases list even though they have a static IP?

    Or maybe a better question, why are the client computers getting an address from the DHCP server even though I have given them a static IP??

     

    thank you

    Tuesday, November 30, 2010 9:11 PM

Answers

  • Magicrecon,

     

    Thank you for all your help, I am still interested in solving this issue, but unfortunately our contract with this particular business ran out and we are no longer working on the project. I will no longer have access to this site for testing. You gave great suggestions. I wish I could continue working on the issue. Good luck with you similar issue.

     

    thanks again.

    • Marked as answer by _-slick-_ Wednesday, December 08, 2010 6:25 AM
    Wednesday, December 08, 2010 6:25 AM

All replies

  • Are the configurations changed in the client systems? Please confirm and let us know the result.
    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. ”
    Thursday, December 02, 2010 7:23 AM
  • I am sorry for the delay. I will try to reply quicker, but I am only at this location a couple hours a day and yesterday I was not even in the office. I have gotten specs from the server and from a windows 7 machine that is using a Static IP, but  the client is still showing up on the DHCP Address Leases list.

    Server Specs:

      Windows Server Standard 2008 SP2 32-bit

      4.00 GB RAM

      2x Intel Xeon 3.60GHz procs

      IP --> XXX.XXX.XXX.21

      SN --> 255.255.255.128

      DG --> XXX.XXX.XXX.1

      DNS 1 --> XXX.XXX.XXX.21

      DNS 2 --> XXX.XXX.XXX.25

     

    Windows 7 Client Machine:

      Windows 7 Professional 32-bit

      4.00 GB Installed RAM (3.00 GB being used)

      Intel Core 2 Quad CPU Q9550 @ 2.83GHz

      IP --> XXX.XXX.XXX.116

      SN --> 255.255.255.128

      DG --> XXX.XXX.XXX.1

      DNS 1 --> XXX.XXX.XXX.21

      DNS 2 --> XXX.XXX.XXX.25

     

    Note: The X's do not change. They represent the same number on the server and the client.

     

    As you can see the client machine shows a static IP of XXX.XXX.XXX.116, but I have verified the DHCP Address Leases List showing this computer leasing XXX.XXX.XXX.53.

     

    Also, the IPCONFIG /ALL output showed "XXX.XXX.XXX.116 (Preferred)" and DHCP Enable = No. I've only seen a "(Preferred)" next to an IPv4 or IPv6 address if it is using DHCP, but this computer is set to use static.

    Is it possible that the windows 7 operating system is leasing an address in addition to using the static?

    Friday, December 03, 2010 12:08 AM
  • I have the same problem, can it be that the static ip's given to the PC's do not have internet acces ? Maybe Windows 7 is repairing the connection automaticly to get internet access. I can't find any clients with static ip's and internet access in the DHCP list.

    if you do a "troubleshoot problems" on the NIC, it does 2 DHCP requests, eventhough it has a static, non internet, IP.

     

    Another option is the fact that the pc's are Vpro enabled and maybe asking for a second adress for the Vpro management.

     

    Just giving you my findings, hoping the problem is solved faster.

    Friday, December 03, 2010 10:57 AM
  • Magicrecon,

    I'm sorry you're experiencing the same problem, but I'm glad to hear I'm not the only one with the issue. All of the client computers with static IP addresses connect to the internet just fine. I do have one client in my DHCP scope that is using a static IP, and you are correct. That computer does not show up in the DHCP Address Leases List.

    I'll have to look more into the Vpro management, but remember, most of my clients have a static IP and do NOT show up on the DHCP Address Leases List. It is only about an average of 10 out of the 50 or so clients with a Static IP that show up on this list.

    The next information I will grab is the IPCONFIG /ALL output of a client with a static IP on the same network that DOES NOT show up on the DHCP Address Leases list.  Hopefully that output can show me a difference between the two machines.

     

    Thanks for the response, hopefully we can get this resolved quickly.

    Friday, December 03, 2010 3:30 PM
  • Here is some more information that may be helpful. The lease time is only 24 hours. I'm looking at the Lease Expiration for the all the computers on the list and they were ALL leased in the morning around the times of 6:00am, 7:00am, and 8:00am. If you're not catching my drift, this is when most people arrive at work and turn on their computer.

    This information doesn't completely disregard the Vpro Technology suggestion, but my understanding of Vpro is that it will send DHCP requests when the computer is in an OFF state. Since all the requests were made right around the start of a typical work day, I would say these computers are requesting addresses in the morning when the computers are booted.

     

    Please let me know if you disagree with what I'm saying. Thanks again

    Friday, December 03, 2010 4:14 PM
  • Do they try PXE boot, and keep the lease untill the next day ?

     

    over here we set the lease to 1h and it keeps on asking for renews all day long. eventhough you can't ping the adress. it also doesn't show the PC name in the list of leases. Which it does for leases asked by pc's which are set to DHCP (and you can ping those pc's on that adress)

    Monday, December 06, 2010 8:40 AM
  • I hope for a breaktrough. while deploying a new system is noticed the default setting for NetBIOS is :

    Use netbios setting from the DHCP server. If static IP address is used or the DHCP server does not provide NetBios setting enable NetBios over TCP/IP

    IIRC 'enable netbios over TCP/IP' is default in XP

    i'll keep you posted if this is the sollution.

     

    Tuesday, December 07, 2010 10:05 AM
  • Magicrecon,

     

    Thank you for all your help, I am still interested in solving this issue, but unfortunately our contract with this particular business ran out and we are no longer working on the project. I will no longer have access to this site for testing. You gave great suggestions. I wish I could continue working on the issue. Good luck with you similar issue.

     

    thanks again.

    • Marked as answer by _-slick-_ Wednesday, December 08, 2010 6:25 AM
    Wednesday, December 08, 2010 6:25 AM
  • Just set a deny on the MAC addresses that you don't want...

    This is done from the DHCP server

    Friday, May 25, 2012 10:50 PM