CURLOPT_IPRESOLVE man page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_IPRESOLVE, long resolve);

Allows an application to select what kind of IP addresses to use when resolving host names. This is only interesting when using host names that resolve addresses using more than one version of IP. The allowed values are:

CURL_IPRESOLVE_WHATEVER

Default, resolves addresses to all IP versions that your system allows.

CURL_IPRESOLVE_V4

Resolve to IPv4 addresses.

CURL_IPRESOLVE_V6

Resolve to IPv6 addresses.

CURL_IPRESOLVE_WHATEVER

All

CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/foo.bin");

  /* resolve host name using IPv6-names only */
  curl_easy_setopt(curl, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V6);

  ret = curl_easy_perform(curl);

  curl_easy_cleanup(curl);
}

Always

Returns CURLE_OK

CURLOPT_HTTP_VERSION(3), CURLOPT_SSLVERSION(3),

curl_easy_setopt(3), CURLOPT_DNS_SHUFFLE_ADDRESSES(3), CURLOPT_PROXY_SSLVERSION(3), CURLOPT_RESOLVE(3), CURLOPT_SSLVERSION(3), libcurl-security(3).