I would recommend to try without explicitly setting DNS server and timeout - just to use the default DNS system settings. Maybe, the "8.8.8.8" is not routable in your setup.
Also, I would run Wireshark or tcpdump to see if your DNS queries/response were actually sent/received on the wire. Thanks, Dmitry Karpov -----Original Message----- From: curl-library <curl-library-boun...@lists.haxx.se> On Behalf Of Luis Carlos Chalaca Figueira via curl-library Sent: Tuesday, October 31, 2023 10:08 AM To: curl-library@lists.haxx.se Cc: Luis Carlos Chalaca Figueira <luisccfigue...@gmail.com> Subject: [EXTERNAL] "Could not resolve host" error only on the multi interface 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], CURLOPT_DNS_SERVERS, "8.8.8.8");. 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 @ 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 -- Unsubscribe: https://lists.haxx.se/mailman/listinfo/curl-library Etiquette: https://curl.se/mail/etiquette.html