CURLOPT_DNS_CACHE_TIMEOUT(3)

1CURLOPT_DNS_CACHE_TIMEOUT(3)curl_easy_setopt optionsCURLOPT_DNS_CACHE_TIMEOUT(3)
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NAME

6       CURLOPT_DNS_CACHE_TIMEOUT - life-time for DNS cache entries
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SYNOPSIS

9       #include <curl/curl.h>
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11       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_CACHE_TIMEOUT, long age);
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DESCRIPTION

14       Pass  a  long,  this sets the timeout in seconds. Name resolves will be
15       kept in memory and used for this number of seconds. Set to zero to com‐
16       pletely disable caching, or set to -1 to make the cached entries remain
17       forever. By default, libcurl caches this info for 60 seconds.
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19       The name resolve functions of various libc implementations do  not  re-
20       read name server information unless explicitly told so (for example, by
21       calling res_init(3)). This may cause libcurl to keep  using  the  older
22       server even if DHCP has updated the server info, and this may look like
23       a DNS cache issue to the casual libcurl-app user.
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25       Note that DNS entries have a "TTL" property but libcurl  does  not  use
26       that.  This  DNS cache timeout is entirely speculative that a name will
27       resolve to the same address for a certain small amount of time into the
28       future.
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DEFAULT

31       60
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PROTOCOLS

34       All
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EXAMPLE

37       CURL *curl = curl_easy_init();
38       if(curl) {
39         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
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41         /* only reuse addresses for a short time */
42         curl_easy_setopt(curl, CURLOPT_DNS_CACHE_TIMEOUT, 2L);
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44         ret = curl_easy_perform(curl);
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46         /* in this second request, the cache will not be used if more than
47            two seconds have passed since the previous name resolve */
48         ret = curl_easy_perform(curl);
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50         curl_easy_cleanup(curl);
51       }
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AVAILABILITY

54       Always
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RETURN VALUE

57       Returns CURLE_OK
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