Chrome's configuration of the Windows DNS Client

[Liam Brown]

Hello,

I would like to request information on how Chrome chooses to configure the Windows DNS Client.  I observe that the behavior of the Windows DNS Client changes drastically once Chrome (the browser) is booted on my Windows 10 machine with its internal DNS client OFF.  Notably, affected behaviors include DNS server timeouts and fail-over behavior.  After observing Chrome's interactions with Windows API through Procmon and Apimonitor, and after extensive review of Chrome's open source code, I am still unable to determine the means by which Chrome configures the DNS Client.

My only lead on this issue was obtained with Procmon.  When I modified(added) a registry key at HKLM\System\CurrentControlSet\Services\Dnscache\Parameters, I observed chrome.exe query the values of a TON of keys in this directory.  Most of these reqistry keys are COMPLETELY UNDOCUMENTED by Microsoft, and none of them are present by default (therefore the queries all returned NAME_NOT_FOUND).  Surprisingly, I was unable to find reference to these keys withing the Chrome source code.  Can anyone shed light on what is going on here?  I will provide the image I obtained from Procmon.

[PhistucK]

If you cannot find them in the source code, then they are probably queried indirectly (by Windows, as a result of a Windows API call by Chrome).

☆PhistucK

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[Liam Brown]

Ok, that makes sense.

Do you know anything about Chrome changing the timeouts/failover behavior of the DNS Client?

Somehow, the timeout for giving up on the primary server and querying the secondary is only 0.15 seconds instead of 1, and the DNS Client is also unwilling to fall back to temporarily only use the secondary. Any thoughts?

Thanks,
Liam.

[PhistucK]

net-dev might be more helpful.

☆PhistucK