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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), "