Windows 10 DNS server selection process has changed since 20h2.

Stan Morisse 36 Reputation points
2021-03-23T16:03:23.387+00:00

Hi,

Numerous documents specify that as of the release of Windows 10, the dns server selection process is based upon the Network Interface Metric, when having multiple adapters enabled. This is/was also the case when implementing a VPN adapter, for example by implementing Always On VPN.

This no longer seems to be the case since the release of Windows 10 20H2. While installing Windows 10 20H2 and configuring Always On VPN in a split-tunnel model, it turns out that our Wifi adapter has a metric of 5 and the Always On VPN adapter has a metric of 50.
In the past, when using Windows 10 v1909, the DNS servers used to resolve public DNS entries, were the ones of the interface with the lowest metric: The wifi adapter.
Now, after installing Windows 10 v20H2, all of a sudden the lowest metric is not the one used any more. The DNS servers used (verified with nslookup) are the ones on the Always On VPN adapter.

I have found no documention, stating that the dns server selection process has changed.
Can someone help me out with this one?

Windows 10 Network
Windows 10 Network
Windows 10: A Microsoft operating system that runs on personal computers and tablets.Network: A group of devices that communicate either wirelessly or via a physical connection.
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  1. Sunny Qi 10,896 Reputation points Microsoft Vendor
    2021-03-24T09:25:52+00:00

    Hi,

    Thanks for posting in Q&A platform.

    I didn't find any official document indicates that DNS resolver priority has changed in 20H2 version. Actually, I have test in my lab with a device with 2 ethernet adapters, the DNS resolver's priority is still determined by the interface metric.

    Please understand, due to the environmental limitation, we have no such WiFi device to test in our lab. It is hard for us to reproduce and analyze this issue from Q&A platform support level.

    If your issue is urgent, I would suggest you open a case with Microsoft where more in-depth investigation can be done so that you would get a more satisfying explanation and solution to this issue.

    You may find phone number for your region accordingly from the link below:

    https://support.microsoft.com/en-us/gp/customer-service-phone-numbers

    Best Regards,
    Sunny

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