Host-only adapter slows down DNS resolution tremendously

[Michael-O]

I have tried VB 4.2.10 and 4.1.24 with the same result.

I recently compiled libcurl myself for a custom client. DNS resolution was awefully slow, around 5 to 10 seconds. After a ​post to the mailing list. I have figured out that when I disable the Host-only adapter, resolution screams again.

With host-only disabled:

D:\workspace-4.2\curlsimple\Debug>curlsimple.exe http://www.virtualbox.org
Provided URL: http://www.virtualbox.org
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   247  100   247    0     0    606      0 --:--:-- --:--:-- --:--:--   631
Name lookup time: 0.016000 s
Connect time: 0.187000 s
Pretransfer time: 0.016000 s
start transfer time: 0.188000 s
Total time: 0.407000 s

With host-only enabled:

D:\workspace-4.2\curlsimple\Debug>curlsimple.exe http://www.virtualbox.org
Provided URL: http://www.virtualbox.org
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   247  100   247    0     0     47      0  0:00:05  0:00:05 --:--:--    57
Name lookup time: 4.844000 s
Connect time: 0.188000 s
Pretransfer time: 0.000000 s
start transfer time: 0.187000 s
Total time: 5.219000 s

There must be something intercepting and blocking DNS resolution for some reason.

I am on Windows XP SP3, compiled libcurl 7.29.0 with mingw/gcc 4.7.2.

[Michael-O]

Similar issues are:

https://www.virtualbox.org/ticket/6051
https://www.virtualbox.org/ticket/3992
https://www.virtualbox.org/ticket/9013
https://www.virtualbox.org/ticket/6745
https://www.virtualbox.org/ticket/3851