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 12Added-in: 7.60.0 13--- 14 15# NAME 16 17CURLOPT_DNS_SHUFFLE_ADDRESSES - shuffle IP addresses for hostname 18 19# SYNOPSIS 20 21~~~c 22#include <curl/curl.h> 23 24CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SHUFFLE_ADDRESSES, long onoff); 25~~~ 26 27# DESCRIPTION 28 29Pass a long set to 1 to enable this option. 30 31When a name is resolved and more than one IP address is returned, this 32function shuffles the order of all returned addresses so that they are used in 33a random order. This is similar to the ordering behavior of the legacy 34gethostbyname function which is no longer used on most platforms. 35 36Addresses are not reshuffled if name resolution is completed using the DNS 37cache. CURLOPT_DNS_CACHE_TIMEOUT(3) can be used together with this 38option to reduce DNS cache timeout or disable caching entirely if frequent 39reshuffling is needed. 40 41Since the addresses returned are randomly reordered, the order is not in 42accordance with RFC 3484 or any other deterministic order that may be 43generated by the system's name resolution implementation. This may have 44performance impacts and may cause IPv4 to be used before IPv6 or vice versa. 45 46# DEFAULT 47 480 (disabled) 49 50# %PROTOCOLS% 51 52# EXAMPLE 53 54~~~c 55int main(void) 56{ 57 CURL *curl = curl_easy_init(); 58 if(curl) { 59 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); 60 curl_easy_setopt(curl, CURLOPT_DNS_SHUFFLE_ADDRESSES, 1L); 61 62 curl_easy_perform(curl); 63 64 /* always cleanup */ 65 curl_easy_cleanup(curl); 66 } 67} 68~~~ 69 70# %AVAILABILITY% 71 72# RETURN VALUE 73 74CURLE_OK or an error such as CURLE_UNKNOWN_OPTION. 75