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| .TH CURLOPT_DNS_SHUFFLE_ADDRESSES 3 "3 March 2018" "libcurl 7.60.0" "curl_easy_setopt options" |
| .SH NAME |
| CURLOPT_DNS_SHUFFLE_ADDRESSES \- Shuffle addresses when a hostname returns more than one |
| .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), " |
