CURLOPT_DNS_CACHE_TIMEOUT(3curl_easy_setopt optionCURLOPT_DNS_CACHE_TIMEOUT(3)
NAME
CURLOPT_DNS_CACHE_TIMEOUT - life-time for DNS cache entries
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_CACHE_TIMEOUT, long age);
DESCRIPTION
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 com-
pletely 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 do not 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 does not 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.
DEFAULT
60
PROTOCOLS
All
EXAMPLE
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
/* only reuse addresses for a 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);
}
AVAILABILITY
Always
RETURN VALUE
Returns CURLE_OK
SEE ALSO
CURLOPT_DNS_USE_GLOBAL_CACHE(3), CURLOPT_DNS_SERVERS(3), CURLOPT_RE-
SOLVE(3),
libcurl 7.81.0 November 26, 2021 CURLOPT_DNS_CACHE_TIMEOUT(3)
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