php_network_getaddresses: getaddrinfo failed

function checkLink ($link)
{
$link = trim($link);
$sock = fsockopen($link, 80, $errnum, $errstr, 30);
if (!$sock) 
$return = "Keine Verbindung";
else 
{
$dump .= "HEAD $link HTTP/1.1\r\n";
$dump .= "User-Agent: TWT Link-Checker\r\n";
$dump .= "Host: 80\r\nConnection: close\r\n";
$dump .= "Connection: close\r\n\r\n";
fputs($sock, $dump);
while($str = fgets($sock, 1024)) 
{
echo ($str);
}
}
fclose($sock);
} // function checkLink ($link)
checkLink ("http://www.rambler.ru");

Warning: fsockopen(): php_network_getaddresses: getaddrinfo failed: Name or service not known in /home/user1/public_html/linkchecker/checklink.php on line 7