---
name: "CURLOPT_DNS_INTERFACE"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_DNS_INTERFACE"
---

# CURLOPT\_DNS\_INTERFACE(3)

interface to speak DNS over

## NAME

CURLOPT\_DNS\_INTERFACE - interface to speak DNS over

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_INTERFACE, char *ifname);
```

## DESCRIPTION

Pass a char pointer as parameter. Set the name of the network interface that the DNS resolver should bind to. This must be an interface name (not an address). Set this option to NULL to use the default setting (do not bind to a specific interface).

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

## DEFAULT

NULL

## PROTOCOLS

All protocols except file:// - protocols that resolve host names.

## 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_INTERFACE, "eth0");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

Added in 7.33.0. This option also requires that libcurl was built with a resolver backend that supports this operation. The c-ares backend is the only such one.

## RETURN VALUE

Returns CURLE\_OK if the option is supported, CURLE\_UNKNOWN\_OPTION if not, or CURLE\_NOT\_BUILT\_IN if support was disabled at compile-time.

## SEE ALSO

[**CURLOPT\_DNS\_LOCAL\_IP4**(3)](/CURLOPT_DNS_LOCAL_IP4/3.md), [**CURLOPT\_DNS\_LOCAL\_IP6**(3)](/CURLOPT_DNS_LOCAL_IP6/3.md), [**CURLOPT\_DNS\_SERVERS**(3)](/CURLOPT_DNS_SERVERS/3.md), [**CURLOPT\_INTERFACE**(3)](/CURLOPT_INTERFACE/3.md)