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Something change my current LAPTOP DNS entry, each 15 minutes, and replace it with a previous DHCP leasing adquired earlier. RRS feed

  • Question

  • Hello, thanks in advance for your help, I would like to know if somebody knows what could be changing my current Laptop ip address in my DNS, each 15 or 20 minutos, and replace it with a previous DHCP leasing that was adquired earlier than my current IP Address, this is happening all day.

    To fix that I run the IPCONFIG /REGISTERDNS command, and that works, it updates my laptop DNS entry, but it takes 15 or 20 minutes to apply again my previous leasing.

    My Windows environment is:

    - 2 DC's Windows Server 2008 R2 SP1 full patched, anyone with their DNS service installed

    - 1 DC Windows Server 2012 R2 full patched, with its DNS service installed.

    - 2 DHCP servers in 50/50 load balancing configuration.

    - All DHCPs are into the DNSUPDATEPROXY group.

    - DHCP is configured to always update DNS entries in the name of clients.


    I'am going to detail step by step what happens:

    1. My laptop request an IP Address from DHCP

    2. DHCP assigns the 192.168.21.20 IP Address.

    3. DHCP update or create DNS entry for my laptop with IP, 192.168.21.20/24

    4. after that I move to another place and my laptop request IP Address for a VLAN in that area.

    5. DHCP makes a second lease for my laptop in the range 192.168.30.80/24

    6. DHCP update the first laptop entry to the current IP Address, 192.168.30.80/24

    7. I ping my laptop DNS registry and it give back my current IP address, 192.168.30.80.

    8. After 15 or 20 minutes, my current IP address in DNS is replaced by something come back to the previous IP address assigned in the step 2.

    9. I run the IPCONFIG /REGISTERDNS in my laptop and it updates the DNS entry again with my current IP address, assigned in step 5.

    10. I run again IPCONFIG /REGISTERDNS and after that it occurs again that my Laptop DNS entry go back to the previous IP address.

    11. I delete the previous lease directly in the DHCP, i refer to the IP address assigned in the step 2.

    12. That day it doesn't happend again that day.

    My question is, is that behavior normal in DHCP?, it should change DNS entry from a DHCP lease that is not using my laptop in that moment? It is not supposed that the DHCP should update the DNS entries only when the lease just happend and don't replace it again, unless, my laptop request again the previous leasing?

    Regards

    Felxs


    Felx



    • Edited by Felx Wednesday, August 2, 2017 12:58 AM
    Tuesday, August 1, 2017 9:56 PM

All replies

  • Hi,Felx

    I suggest you configure your DHCP option like the figure below.

    Inbox discard A andPTR records when lease is deleted.

    And try again.

    Best Regards,
    Frank


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    Wednesday, August 2, 2017 7:33 AM
  • Hello Frank, thanks for your answer, really that option was already enabled, I would like to explain that the problem was not, that the DHCP don´t delete the A and PTR records when lease is deleted, actually the DHCP replace any A and PTR record when a new lease is assigned to the client, the problem was that after that, any previous lease assigned for the DHCP to the same PC in other scopes used before for the client, they rewrite the current DNS record for that PC's, also when the PC continue using the last IP delivered to it fro the DHCP, that behavior only stops when I delete the previous leasings for other scopes in the DHCP a left the last (current) lease in use.

    I don´t know why this behavior of replacing the DNS record for that devices with previous leases that are not in use in that moment and overwrite the leases currently in use for that device on the DNS record.

    Thanks in advance.

    felxs


    Felx

    Thursday, August 3, 2017 7:41 AM