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Re: DNS resolution performance woeful while CRC is running in Windows

Thanks for pointing that out, when crc starts, I do see:

INFO Will run as admin: add dns server address to interface vEthernet (Default Switch)

I also noticed in my ipconfig /all, that a bunch of the vEthernet interfaces have these IPv6 link-local DNS addresses:

   DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1                                                                        
                                       fec0:0:0:ffff::2%1                                                                                                               fec0:0:0:ffff::3%1                                                                        

Which don't seem to be a problem until crc starts.  So maybe whatever crc does to make the name resolution work, inadvertently enables resolution via IPv6 nameservers somehow, causing it to try and resolve names via the above DNS servers.

From what I can tell those DNS servers seem fairly common, I don't exactly know where they come from, or how they're supposed to work.  I suspect if I go through all my interfaces disabling ipv6 then the DNS issue will go away.



On Mon, 7 Oct 2019 at 22:40, Walther, Jens-Uwe <jens-uwe walther proservia de> wrote:

Hi, I had an CRC issue and one of the developer stated that the default Hyper-V network switch “Default switch” is the one who is “hosting” the

crc.testing domain via DHCP in some kind.


Beste Grüße / Best regards

Jens-Uwe Walther

M: +49 (160) 97250976


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Betreff: DNS resolution performance woeful while CRC is running in Windows


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I'm wondering if someone can let me know how the crc.testing domain works in crc for windows?


I can't see any entries in c:\windows\system32\drivers\etc\hosts, and my DNS entries appear to be the same, but a dig command doesn't find api.crc.testing, so it's doing something special to get that name resolution to work.


When crc is running, DNS resolution performance in chrome and edge, is woeful, around the 10-second mark.


Once I ran crc stop then DNS performance went back to normal. 


I'm running Windows 10, Windows Insiders Build 18990 (fast ring).


I went hunting through "ipconfig /all", but haven't found anything.







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