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CURLOPT_DNS_CACHE_TIMEOUT(3)                          curl_easy_setopt options

NAME

CURLOPT_DNS_CACHE_TIMEOUT - set 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 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.

DEFAULT

60

PROTOCOLS

All

EXAMPLE

CURL *curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "http://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); }

AVAILABILITY

Always

RETURN VALUE

Returns CURLE_OK

SEE ALSO

CURLOPT_DNS_USE_GLOBAL_CACHE(3), CURLOPT_DNS_SERVERS(3), CURLOPT_RESOLVE(3), libcurl 7.65.3 December 9, 2017 CURLOPT_DNS_CACHE_TIMEOUT(3)

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