curl/docs/libcurl/opts/CURLOPT_DNS_SHUFFLE_ADDRESSES.3

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.TH CURLOPT_DNS_SHUFFLE_ADDRESSES 3 "3 March 2018" libcurl libcurl
.SH NAME
CURLOPT_DNS_SHUFFLE_ADDRESSES \- shuffle IP addresses for hostname
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SHUFFLE_ADDRESSES, long onoff);
.fi
.SH DESCRIPTION
When a name is resolved and more than one IP address is returned, shuffle the
order of all returned addresses so that they will be used in a random order.
This is similar to the ordering behavior of gethostbyname which is no longer
used on most platforms.

Addresses will not be reshuffled if a name resolution is completed using the
DNS cache. \fICURLOPT_DNS_CACHE_TIMEOUT(3)\fP 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 will be reordered randomly, their order will not
be 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.
.SH DEFAULT
0 (disabled)
.SH PROTOCOLS
All
.SH EXAMPLE
.nf
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);
}
.fi
.SH AVAILABILITY
Added in 7.60.0
.SH RETURN VALUE
CURLE_OK or an error such as CURLE_UNKNOWN_OPTION.
.SH "SEE ALSO"
.BR CURLOPT_DNS_CACHE_TIMEOUT "(3), " CURLOPT_IPRESOLVE "(3), "