how to troubleshooting a DCHP+DNS dynamic update A record issue

Question

Hi Experts

We have a DNS server (domain controller), and another DHCP server.

Followed https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-2000-server/cc959284(v=technet.10) to configure a dynamic update on DHCP server, which means DNS and DHCP integration.

1. The DHCP server was added to DNSupdateProxy group.
2. The DNS server was configured to securely dynamic update only.

1. The DHCP server was configured to "Dynamic Update only if requested by the client", and "Discard A record when lease expired", no "name protection".

I just find that the below credential isn't configured. (not sure why)

There are some stale A records was not deleted automatically by DHCP server as expected.

Is there any way that I can check the security connection(or securely update the A record) process between the DHCP server and DNS server ? event ID? or WireShark to capture the packet?

I suspect the Dynamic update from DHCP server was not working properly.

Thanks in advance

Answer 1

Hello,

Troubleshooting Dynamic DNS (DDNS) and DHCP integration issues can involve a few different steps to identify the problem. Here are some steps you can take to diagnose and resolve the issue:

Event Logs:

Check the event logs on both the DHCP server and the DNS server for any relevant errors or warnings. Look for events related to DNS dynamic updates, DHCP lease renewals, and any authentication issues.

DNSUpdateProxy Group:

Ensure that the DHCP server is a member of the DNSUpdateProxy group. This group is necessary for DHCP servers to update DNS records on behalf of clients.

DNS Secure Dynamic Updates:

Make sure that the DNS server is configured to allow secure dynamic updates. This ensures that only authorized clients can update DNS records.

DHCP Server Configuration:

Double-check the DHCP server configuration to ensure that it's set up correctly for DDNS. The settings you mentioned ("Dynamic Update only if requested by the client" and "Discard A record when lease expired") are generally appropriate for typical DDNS scenarios.

Credentials for DNS Updates:

As you mentioned, the credentials for DNS updates might not be configured. Configure these credentials in the DHCP server settings. They are used for updating DNS records on the DNS server. Use a user account that has the necessary permissions to update DNS records.

Packet Capture:

Using a tool like Wireshark to capture network traffic between the DHCP server and the DNS server can provide insights into whether the communication for DDNS updates is occurring as expected. Look for DNS update requests and responses.

Manual DNS Updates:

If you suspect DDNS issues, try manually updating DNS records for a client with an IP address leased by the DHCP server. This can help confirm whether the DDNS process is functioning correctly.

Stale Records:

Stale DNS records that aren't being deleted could be caused by various factors, including DNS scavenging settings. Check the DNS scavenging settings on the DNS server and ensure that they are configured appropriately.

Network and Firewall Considerations:

Ensure that there are no network or firewall issues preventing communication between the DHCP server and the DNS server. Sometimes, firewalls or network security settings can block the necessary communication.

Windows Update and Patches:

Make sure that both the DHCP and DNS servers have the latest Windows updates and patches installed. Sometimes, issues can arise due to outdated software.

Testing in a Controlled Environment:

If possible, set up a controlled testing environment where you can simulate DHCP lease renewals and observe how DDNS updates are handled. This can help isolate the issue and troubleshoot more effectively.

Remember that troubleshooting networking issues can sometimes be complex and iterative. It's important to document your steps and changes so that you can track your progress and undo any changes that don't yield the desired results.

I used AI provided by ChatGPT to formulate part of this response. I have verified that the information is accurate before sharing it with you.

Hope this resolves your Query !!

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