A me facendo così funziona in parte:

Codice PHP:
$url='http://whois.domaintools.com/78.15.185.217';
$stringa=file_get_contents($url);
echo("$stringa"); 
in pratica mi visualizza la parte superiore della pagina e mi da questa scritta:

codice:
 Security : Client may be too resource intensive. Please contact us in person to resolve the issue. Access will be denied until issue is resolved. (Code 2)

Contact us at Domain Tools Support.