i've writed some Php code that lookup for domain (whois) but it fails !!

this is some of my code :

function checkdomain($server,$domain){
global $response;
    $connection = fsockopen($server,43);
    fputs($connection, "domain " . $domain . "\r\n");
    while(!feof($connection)){
        $response .= fgets($connection, 4096);
    }
    fclose($connection);
}
checkdomain("whois.crsnic.net","www.example.com");

the code work on my localhost ( apache,php,mysql, OS -> Win XP ) but when i uploaded it to my host (Linux) it failed. and i always see the Below Error/message :

Warning: fsockopen() [function.fsockopen]: unable to connect to whois.crsnic.net:43 (Network is unreachable) in /home/hamid0011/public_html/whois/whois.php on line 37

what should i do ? is this my host's problem or whois server ( but it work in localhost ) or my code ?

TNX