curl / libcurl / API / curl_easy_setopt / CURLOPT_DNS_SERVERS

CURLOPT_DNS_SERVERS explained

Name

CURLOPT_DNS_SERVERS - DNS servers to use

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SERVERS, char *servers);

Description

Pass a char pointer that is the list of DNS servers to be used instead of the system default. The format of the dns servers option is:

host[:port][,host[:port]]...

For example:

192.168.1.100,192.168.1.101,3.4.5.6

The application does not have to keep the string around after setting this option.

Using this option multiple times makes the last set string override the previous ones. Set it to NULL to disable its use again.

Default

NULL

Protocols

This functionality affects all supported protocols

Example

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
    curl_easy_setopt(curl, CURLOPT_DNS_SERVERS,
                     "192.168.1.100:53,192.168.1.101");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Notes

This option requires that libcurl was built with a resolver backend that supports this operation. The c-ares backend is the only such one.

Availability

Added in curl 7.24.0

Return value

Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, CURLE_NOT_BUILT_IN if support was disabled at compile-time, CURLE_BAD_FUNCTION_ARGUMENT when given an invalid server list, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.