为什么'www。'网址前缀会影响cURL是否可以抓取网页内容？

Question

Here's my setup:

$url1 = "www.gyngen.dk";
$url2 = "gyngen.dk";

$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);  
curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 20);  
$result = curl_exec($curl);
curl_close($curl);

Using $url1 will result in an empty string and $url2 will work as intended. But why my fellow stackoverflowians, is cURL so delicate when it comes to the presence of ‘www.’ , when it (in my experience) doesn’t matter when using URLs in my browser (firefox).

Thanks in advance!

Answer 1

http://www.gyngen.dk redirects to http://gyngen.dk.

Your browser follows the redirect transparently.

PHP/cURL, with your settings, does not. This question explains how to change that.