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                     23: .TH CURLOPT_DNS_CACHE_TIMEOUT 3 "December 09, 2017" "libcurl 7.70.0" "curl_easy_setopt options"
                     24: 
                     25: .SH NAME
                     26: CURLOPT_DNS_CACHE_TIMEOUT \- set life-time for DNS cache entries
                     27: .SH SYNOPSIS
                     28: #include <curl/curl.h>
                     29: 
                     30: CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_CACHE_TIMEOUT, long age);
                     31: .SH DESCRIPTION
                     32: Pass a long, this sets the timeout in seconds. Name resolves will be kept in
                     33: memory and used for this number of seconds. Set to zero to completely disable
                     34: caching, or set to -1 to make the cached entries remain forever. By default,
                     35: libcurl caches this info for 60 seconds.
                     36: 
                     37: The name resolve functions of various libc implementations don't re-read name
                     38: server information unless explicitly told so (for example, by calling
                     39: \fIres_init(3)\fP). This may cause libcurl to keep using the older server even
                     40: if DHCP has updated the server info, and this may look like a DNS cache issue
                     41: to the casual libcurl-app user.
                     42: 
                     43: Note that DNS entries have a "TTL" property but libcurl doesn't use that. This
                     44: DNS cache timeout is entirely speculative that a name will resolve to the same
                     45: address for a certain small amount of time into the future.
                     46: .SH DEFAULT
                     47: 60
                     48: .SH PROTOCOLS
                     49: All
                     50: .SH EXAMPLE
                     51: .nf
                     52: CURL *curl = curl_easy_init();
                     53: if(curl) {
                     54:   curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/foo.bin");
                     55: 
                     56:   /* only reuse addresses for a very short time */
                     57:   curl_easy_setopt(curl, CURLOPT_DNS_CACHE_TIMEOUT, 2L);
                     58: 
                     59:   ret = curl_easy_perform(curl);
                     60: 
                     61:   /* in this second request, the cache will not be used if more than
                     62:      two seconds have passed since the previous name resolve */
                     63:   ret = curl_easy_perform(curl);
                     64: 
                     65:   curl_easy_cleanup(curl);
                     66: }
                     67: .fi
                     68: .SH AVAILABILITY
                     69: Always
                     70: .SH RETURN VALUE
                     71: Returns CURLE_OK
                     72: .SH "SEE ALSO"
                     73: .BR CURLOPT_DNS_USE_GLOBAL_CACHE "(3), " CURLOPT_DNS_SERVERS "(3), "
                     74: .BR CURLOPT_RESOLVE "(3), "