$rbl = new DNSRBL(
    array(
        'dnsbl' => array(
            'sbl.spamhaus.org'
        ),
        'surbl' => array(
            'dbl.spamhaus.org'
        )
    )
);

//checks the surbl
var_export($rbl->isListed('dbltest.com')); echo ";\n";

//checks the dnsbl
var_export($rbl->getListingBlacklists('127.0.0.2')); echo ";\n";

true;
array (
  0 => 'sbl.spamhaus.org',
);