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"Could not resolve host" error only on the multi interface

From: Luis Carlos Chalaca Figueira via curl-library <>
Date: Tue, 31 Oct 2023 17:07:52 +0000

Hello everybody,

I'm building a web crawler.

Started with python but the need for speed led me to libcurl.

The obstacle I'm having is: when using the multi interface a big part of
the the connections cloe because of the error "Could not resolve host:"

What I've tried:

1 - Confirmed that all URLs are correct.

2 - Confirmed that using the easy interface URLs are resolved.

3 - Confirmed that other programs like dig, resolvectl, nslookup can
resolve URLs that multi interface couldn't.

4 - Set a "reputable" DNS server doing: curl_easy_setopt(handles[i],

5 - In the file /etc/nsswitch.conf, line "hosts: files
nDNS[NOTFOUNDED=return] dns" I deleted  [NOTFOUNDED=return].

6 - I've turned verbose on - Doesn't help me much.

I don't know what to do more as it seems a problem inside the library,
so i posted here before going digging in the library.

System info:

O.S. - Ubuntu 22.04.3 LTS

Harware - HP HP Pavilion Laptop 14-ce3xxx

Processor - Intel® Core™ i7-1065G7 CPU _at_ 1.30GHz × 8

libcurl version - 7.81.0

Attached I send the source code file I'm using do debug this problem.

Best Regards,

Luis Figueira

Received on 2023-10-31