DNS configuration issue

Question

Hi,

I have multiple application which runs on medical windows 10 hardware.

As per our product requirement i have blocked applications dialog to appear on main screen but after configuring the dns server i am observing the pop-up dialogue of one of the application and also observing the memory leak.

If i don't configure the DNS server, if it is configured only with IP address i am not seeing any memory leak issue or pop-up.

Only after configuring DNS server i am seeing the memory leak.

It would be good if anyone has any idea why after DNS configuration i am facing the issue.

I am using Windows 10 21H2 IoT LTSC.

***Move from Windows / Windows 10 / Windows update, recovery, and backup***

Answer 1

Thank you for reaching out. Based on your description, the issue seems to be related to configuring the DNS server is somehow triggering network-related behavior in the application, leading to the pop-up dialog and memory leak. Here are a few possible explanations and troubleshooting steps:

Possible Causes

1. Application Dependency on DNS Resolution

Some applications attempt to resolve domain names in the background for licensing, updates, or telemetry. If DNS is configured, these requests might succeed and trigger additional operations (e.g., auto-updates or remote logging), leading to unexpected behavior.

1. Blocking Pop-ups Issue

If you've blocked applications' dialogs using Group Policy or registry tweaks, these settings might not apply uniformly when network resolution is enabled.

The application might be checking for online validation, failing, and throwing a UI dialog.

1. Network Traffic Causing Memory Leak

If the application continuously retries DNS queries due to incorrect settings, failed lookups, or slow responses, it could cause excessive resource consumption, leading to a memory leak.

The leak could also stem from an internal process within the application that behaves differently when DNS is available.

1. Windows IoT LTSC Network Stack Issues

Windows 10 IoT LTSC might handle network stack behavior differently, especially if network-related services (like WinHTTP, WinINET, or DNS Client) are modified or restricted.

1. Firewall or Security Policy Interference

If security policies or firewall rules are different when using DNS, the application might be making additional requests that increase memory usage or cause unwanted UI interactions.

Troubleshooting Steps

✅ 1. Monitor DNS Requests

Use Wireshark or Microsoft Message Analyzer to check which DNS queries are being made when the issue occurs.

If you see continuous lookups or repeated failed resolutions, that could indicate a loop causing memory buildup.

✅ 2. Check Application Logs

Open Event Viewer (eventvwr.msc) and check under Windows Logs > Application for any errors or warnings related to the application.

✅ 3. Test with a Local Dummy DNS

Set up a local DNS server (e.g., Dnsmasq or Windows DNS Server) and point the device to it.

Observe whether the pop-up or memory leak persists. If the issue disappears, external DNS resolution could be a trigger.

✅ 4. Disable Online Features

If the application has settings related to automatic updates, logging, or online features, disable them and test.

✅ 5. Test with a Static Hosts File

Instead of using DNS, try adding critical domain entries manually in C:\Windows\System32\drivers\etc\hosts.

Example:

127.0.0.1 example.com

✅ 6. Check Resource Usage

Open Task Manager (Ctrl+Shift+Esc) or Performance Monitor (perfmon.msc) and monitor memory consumption when DNS is enabled vs. disabled.

✅ 7. Try an Alternative DNS Server

If using an internal DNS server, try switching to a public DNS like Google (8.8.8.8) or Cloudflare (1.1.1.1) and observe if the issue persists.

Next Steps

If you identify a specific process or domain causing the issue, you can block or redirect it using Group Policy, firewall rules, or a proxy.

If the application is proprietary or third-party, contact the vendor to see if they acknowledge any known issues related to network behavior.

Let me know if you need further guidance! 🚀

Answer 2

Hi,

Thank you for the detailed info.

I have tried the same scenario with older OS 1809 (Windows 10 Enterprise LTSC 2019). I have configured the same DNS with older OS and i am not seeing the issue.

So looks like the issue exists in 21h2 OS.(Windows 10 IoT Enterprise LTSC 2021). Any idea of DNS change in 21h2 OS?

Answer 3

Hi,

I have tried the above troubleshooting steps. But i have observed that memory leak is very in-consistent.

Looks like some windows application/services causing this memory leak.

With Windows 1809 looks like it is stable but windows 10 21H2 is causing the problem.

When i tried analyze the memory leak i found that the tags are related to Microsoft file system.

Do you want to check any other things for the above issue?

Answer 4

Hi,

Thank you for the update and for trying the troubleshooting steps.

Since the memory leak issue is inconsistent and you observed that it occurs only in Windows 10 21H2 while Windows 1809 doesn't show this behavior, it does seem that something specific to the 21H2 release is triggering the issue. Given that the tags are related to the Microsoft file system, it could be useful to explore if any new file system or DNS-related updates in 21H2 are interacting with your application.

I would recommend the following next steps:

1. Check for any updates/patches released by Microsoft specifically for the file system or DNS in Windows 10 21H2.
2. Test with a clean boot to rule out any third-party software or services causing the issue.
3. Consider capturing memory dump analysis during the leak occurrence to further isolate the exact culprit.

Let me know if you'd like to proceed with these steps or if you have any other specific insights on the issue.

Answer 5

Thanks for the reply.

I am suspecting schedular tasks causing the issue so i will try disabling below tasks and check:

 MicrosoftEdgeUpdateTaskMachineCore*

 MicrosfotEdgeUpdateTaskMachineUA*

 \Microsoft\Windows\Application Experience\PcaPatchDbTask

 \Microsoft\Windows\Application Experience\PcaWallpaperAppDetect

 \Microsoft\Windows\CloudRestore\Backup

 \Microsoft\Windows\Shell\ThemesSyncedImageDownload

 \Microsoft\Windows\AppxDeploymentClient\UCPD velocity

 \Microsoft\Windows\Windows Defender\Windows Defender Cleanup

 \Microsoft\Windows\Windows Defender\Windows Defender Verification

These tasks were not present in 2019 OS.

What is your thoughts on disabling above tasks?

Given that the tags are related to the Microsoft file system,

it could be useful to explore if any new file system or DNS-related updates in 21H2 are interacting with your application.

• Regarding the File system we are using NTFS file system and the we are using the same application which is used in 2019 OS.

The leak we are seeing in non-pool paged bytes.