Client cannot contact DHCP server after the domain server IP address has changed

Decipher21 1 Reputation point
2021-02-18T08:13:10.417+00:00

Hi Everyone,

I recently change the IP address of our domain controller which happened to be our DNS server and DHCP server as well.
These changes results to our LAN users cannot get the right IP configuration dynamically.
When we provide IP address statically, the computer can connect to the internet.

I already configure the DNS server correctly.
It seems there are missing configuration from the DHCP server that I haven't check.
I'm currently using Windows Server 2016.

Please help.

Windows Server 2016
Windows Server 2016
A Microsoft server operating system that supports enterprise-level management updated to data storage.
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Windows DHCP
Windows DHCP
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.DHCP: Dynamic Host Configuration Protocol (DHCP). A communications protocol that lets network administrators manage centrally and automate the assignment of Internet Protocol (IP) addresses in an organization's network.
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3 answers

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  1. Candy Luo 12,686 Reputation points Microsoft Vendor
    2021-02-19T02:19:05.177+00:00

    Hi ,

    In order to get a more concreted idea of this issue, I would appreciate your help to collect the following information for further troubleshooting:

    1.Would you please post the result of running ipconfig/all at the command prompt on the computer to let us know the machine’s configuration?

    2.Make sure the DNS server is updated in DHCP(option 006).

    69852-image.png

    After DHCP scope option is configured, it will take effect when we ipconfig/release&renew or restart the client.

    3.If you don't want to restart computers, please run the commands in this order on your DHCP clients:

    ipconfig /release

    ipconfig /flushdns

    ipconfig /renew

    Then check if DHCP clients can obtain IP address from DHCP server successfully.

    Best Regards,

    Candy


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  2. Decipher21 1 Reputation point
    2021-02-23T23:59:51.477+00:00

    Hi Candy,

    Thank you for your response.
    Here are the details of the machine.

    1. ipconfig/all machines configuration.
      Server:
      71292-server-04.png

    Client (Cannot get IP from the DHCP):
    71269-client.png

    1. The DNS server is already updated on the DHCP. I already configure it before after I changed the server's IP address.
      Restarting the client was done before but nothings change.
      71313-dns.png
    2. I also try this method but it seems the client cannot communicate with the DHCP server.
      Although the client can PING the server and have internet if was configure statically.

    I appreciate any other solution to the issue.

    Thank you.


  3. Candy Luo 12,686 Reputation points Microsoft Vendor
    2021-02-24T02:50:04.21+00:00

    Hi ,

    I noticed that your DHCP server's IP address and scope range is not in the same subnet.

    71353-image.png

    Based on my understanding, your DHCP server and the client are not in the same subnet and now you need the client to obtain the IP address from DHCP server. Please feel free to let me know if I have any misunderstanding.

    Since DHCP server and client are not in same subnet, the relay agent is required to allow client to obtain IP address from DHCP server. Relay agents are used to forward requests and replies between clients and servers when they are not on the same physical subnet.

    Did you configure DHCP relay agent in your environment? If not, please first configure Relay agent. Relay agent can be configured with on a network device, or you can configure DHCP relay on a Windows Server with the Remote Access role installed.

    For your reference:

    How relay agents work

    For steps to install and configure DHCP Relay Agent in Windows Server 2016, you can refer to the following article:

    DHCP Relay Agent: Configuration in Windows Server 2016

    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    Best Regards,

    Candy

    --------------------------------------------------------------

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