Couldn't resolve host 'www.youtube.com

Couldn't resolve host 'www.youtube.com

$curl =
curl_init("http://www.youtube.com/oembed?url=https://www.youtube.com/watch?v=Bgn7n3OPAqE&format=json");
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
$ret = json_decode(curl_exec($curl),true);
print_r($ret);
$err = curl_errno( $curl );
$errmsg = curl_error( $curl);
echo $err; echo $errmsg;
curl_close($curl);
hey i am trying to get the content in youtube api,but i says could noty
resolve,but when i try via terminal it returns me the array