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* Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
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CURLOPT_DNS_CACHE_TIMEOUT - set life-time for DNS cache entries #include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_CACHE_TIMEOUT, long age); Pass a long, this sets the timeout in seconds. Name resolves will be kept in memory and used for this number of seconds. Set to zero to completely disable caching, or set to -1 to make the cached entries remain forever. By default, libcurl caches this info for 60 seconds. The name resolve functions of various libc implementations don't re-read name server information unless explicitly told so (for example, by calling res_init(3)). This may cause libcurl to keep using the older server even if DHCP has updated the server info, and this may look like a DNS cache issue to the casual libcurl-app user. Note that DNS entries have a "TTL" property but libcurl doesn't use that. This DNS cache timeout is entirely speculative that a name will resolve to the same address for a certain small amount of time into the future. 60 All

CURL *curl = curl_easy_init();
if(curl) {
 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");

 /* only reuse addresses for a very short time */
 curl_easy_setopt(curl, CURLOPT_DNS_CACHE_TIMEOUT, 2L);

 ret = curl_easy_perform(curl);

 /* in this second request, the cache will not be used if more than
 two seconds have passed since the previous name resolve */
 ret = curl_easy_perform(curl);

 curl_easy_cleanup(curl);
}

Always Returns CURLE_OK CURLOPT_DNS_USE_GLOBAL_CACHE "(3), " CURLOPT_DNS_SERVERS "(3), " CURLOPT_RESOLVE "(3), "