NAME

       CURLOPT_DNS_SHUFFLE_ADDRESSES - shuffle IP addresses for hostname

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SHUFFLE_ADDRESSES, long onoff);

DESCRIPTION

       Pass a long set to 1 to enable this option.

       When  a  name is resolved and more than one IP address is returned, this function shuffles
       the order of all returned addresses so that they are used  in  a  random  order.  This  is
       similar  to  the ordering behavior of the legacy gethostbyname function which is no longer
       used on most platforms.

       Addresses are not reshuffled  if  name  resolution  is  completed  using  the  DNS  cache.
       CURLOPT_DNS_CACHE_TIMEOUT(3)  can  be  used  together with this option to reduce DNS cache
       timeout or disable caching entirely if frequent reshuffling is needed.

       Since the addresses returned are randomly reordered, the order is not in  accordance  with
       RFC  3484  or  any  other  deterministic  order that may be generated by the system's name
       resolution implementation. This may have performance impacts and may cause IPv4 to be used
       before IPv6 or vice versa.

DEFAULT

       0 (disabled)

PROTOCOLS

       All

EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
           curl_easy_setopt(curl, CURLOPT_DNS_SHUFFLE_ADDRESSES, 1L);

           curl_easy_perform(curl);

           /* always cleanup */
           curl_easy_cleanup(curl);
         }
       }

AVAILABILITY

       Added in 7.60.0

RETURN VALUE

       CURLE_OK or an error such as CURLE_UNKNOWN_OPTION.

SEE ALSO

       CURLOPT_DNS_CACHE_TIMEOUT(3), CURLOPT_IPRESOLVE(3)