Go to main content

man pages section 3: Library Interfaces and Headers

Exit Print View

Updated: Thursday, June 13, 2019
 
 

CURLOPT_DNS_CACHE_TIMEOUT (3)

Name

CURLOPT_DNS_CACHE_TIMEOUT - time for DNS cache entries

Synopsis

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_CACHE_TIMEOUT, long
age);

Description

curl_easy_setopt options                          CURLOPT_DNS_CACHE_TIMEOUT(3)



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 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 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


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | web/curl         |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
SEE ALSO
       CURLOPT_DNS_USE_GLOBAL_CACHE(3),      CURLOPT_DNS_SERVERS(3),      CUR-
       LOPT_RESOLVE(3),



NOTES
       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source    was    downloaded    from    https://github.com/curl/curl/ar-
       chive/curl-7_64_0.zip

       Further information about this software can be found on the open source
       community website at http://curl.haxx.se/.



libcurl 7.37.0                    17 Jun 2014
                                                  CURLOPT_DNS_CACHE_TIMEOUT(3)