1--- 2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3SPDX-License-Identifier: curl 4Title: CURLOPT_DNS_SHUFFLE_ADDRESSES 5Section: 3 6Source: libcurl 7See-also: 8 - CURLOPT_DNS_CACHE_TIMEOUT (3) 9 - CURLOPT_IPRESOLVE (3) 10Protocol: 11 - All 12--- 13 14# NAME 15 16CURLOPT_DNS_SHUFFLE_ADDRESSES - shuffle IP addresses for hostname 17 18# SYNOPSIS 19 20~~~c 21#include <curl/curl.h> 22 23CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SHUFFLE_ADDRESSES, long onoff); 24~~~ 25 26# DESCRIPTION 27 28Pass a long set to 1 to enable this option. 29 30When a name is resolved and more than one IP address is returned, this 31function shuffles the order of all returned addresses so that they are used in 32a random order. This is similar to the ordering behavior of the legacy 33gethostbyname function which is no longer used on most platforms. 34 35Addresses are not reshuffled if name resolution is completed using the DNS 36cache. CURLOPT_DNS_CACHE_TIMEOUT(3) can be used together with this 37option to reduce DNS cache timeout or disable caching entirely if frequent 38reshuffling is needed. 39 40Since the addresses returned are randomly reordered, the order is not in 41accordance with RFC 3484 or any other deterministic order that may be 42generated by the system's name resolution implementation. This may have 43performance impacts and may cause IPv4 to be used before IPv6 or vice versa. 44 45# DEFAULT 46 470 (disabled) 48 49# EXAMPLE 50 51~~~c 52int main(void) 53{ 54 CURL *curl = curl_easy_init(); 55 if(curl) { 56 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); 57 curl_easy_setopt(curl, CURLOPT_DNS_SHUFFLE_ADDRESSES, 1L); 58 59 curl_easy_perform(curl); 60 61 /* always cleanup */ 62 curl_easy_cleanup(curl); 63 } 64} 65~~~ 66 67# AVAILABILITY 68 69Added in 7.60.0 70 71# RETURN VALUE 72 73CURLE_OK or an error such as CURLE_UNKNOWN_OPTION. 74