After DC change, internet dns resolve problem

Hello,

The delay you’re experiencing is very typical of a DNS timeout issue where one of your DNS servers—likely the newly promoted gasvr24—is not promptly resolving external names either because of misconfigured forwarders, incorrect/absent root hints, or lingering settings from your old DC environment. By verifying and correcting these settings, your internal DNS should be able to resolve external names without the initial delay.

I'm going to make a little troubleshooting for you;

Troubleshooting Steps

1. Check DNS Forwarders in the DNS Manager:
   • On gasvr24 (192.168.128.3) and svr2022 (192.168.128.4), open the DNS Manager.
   • Right-click the server name → Properties → Forwarders tab.
   • Verify that you have valid forwarders or that the root hints are intact.
   • If not configured, adding trusted external DNS servers (like 8.8.8.8 or 1.1.1.1) as forwarders can help ensure prompt resolution.
2. Inspect Root Hints:
   • Still in DNS Manager, check that the Root Hints are correct and up-to-date.
   • Outdated or missing root hints can cause delays as the server struggles to resolve external names via iterative queries.
3. Examine Preferred DNS Server Settings on Your Domain Controllers:
   • Ensure that on gasvr24, the primary DNS setting isn’t pointing to itself in a way that disrupts proper external query processing.
   • Sometimes using the loopback address (127.0.0.1) without proper configuration can contribute to delay.
   • It could be beneficial to have each DC point to the other for DNS or to a known-good forwarder.
4. Clear DNS Caches if Needed:
   • You can clear the DNS cache on the affected server using: cmd

          ipconfig /flushdns
     

   • This ensures that stale entries aren’t contributing to the delay.
5. Review Any Residual Settings from the Old DC:
   • Check for references (in DNS zones, forwarders, or DHCP options) to the old DC’s IP addresses (192.168.128.1 or 192.168.128.2).
   • Ensure they’re completely removed from your configuration.
6. Test Client Settings:
   • As you noticed, if clients use a public DNS like 8.8.8.8 instead of the problematic internal DNS, the delay goes away. This confirms that the primary internal DNS configuration is causing the delay for initial resolution.

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Just following up, Do you need more guidance or assistance ?

I will check all the troubleshooting steps and I will return for a feedback.

Thanks for your reply!