Достаточно простой whois скрипт для основных доменных зон:

$domain = "http://lenta.ru";
$domain = strtolower(trim($domain));
$domain = preg_replace('/^http:\/\//i', '', $domain);
$domain = preg_replace('/^www\./i', '', $domain);
$domain = explode('/', $domain);
$domain = trim($domain[0]);

// split the TLD from domain name
$_domain = explode('.', $domain);
$lst = count($_domain)-1;
$ext = $_domain[$lst];

$servers = array(
    "biz" => "whois.neulevel.biz",
    "com" => "whois.internic.net",
    "us" => "whois.nic.us",
    "coop" => "whois.nic.coop",
    "info" => "whois.nic.info",
    "name" => "whois.nic.name",
    "net" => "whois.internic.net",
    "gov" => "whois.nic.gov",
    "edu" => "whois.internic.net",
    "mil" => "rs.internic.net",
    "int" => "whois.iana.org",
    "ac" => "whois.nic.ac",
    "ae" => "whois.uaenic.ae",
    "at" => "whois.ripe.net",
    "au" => "whois.aunic.net",
    "be" => "whois.dns.be",
    "bg" => "whois.ripe.net",
    "br" => "whois.registro.br",
    "bz" => "whois.belizenic.bz",
    "ca" => "whois.cira.ca",
    "cc" => "whois.nic.cc",
    "ch" => "whois.nic.ch",
    "cl" => "whois.nic.cl",
    "cn" => "whois.cnnic.net.cn",
    "cz" => "whois.nic.cz",
    "de" => "whois.nic.de",
    "fr" => "whois.nic.fr",
    "hu" => "whois.nic.hu",
    "ie" => "whois.domainregistry.ie",
    "il" => "whois.isoc.org.il",
    "in" => "whois.ncst.ernet.in",
    "ir" => "whois.nic.ir",
    "mc" => "whois.ripe.net",
    "to" => "whois.tonic.to",
    "tv" => "whois.tv",
    "ru" => "whois.ripn.net",
    "org" => "whois.pir.org",
    "aero" => "whois.information.aero",
    "nl" => "whois.domain-registry.nl"
);

if(!isset($servers[$ext])) die('Error: No matching nic server found!');

$nic_server = $servers[$ext];
$output = '';

// connect to whois server:
if($conn = fsockopen ($nic_server, 43)) {
    fputs($conn, $domain."\r\n");
    while(!feof($conn)) $output .= fgets($conn,128);    
    fclose($conn);
} else { 
    die('Error: Could not connect to '.$nic_server.'!');
}

echo $output;

Результат запроса для домена lenta.ru:

% By submitting a query to RIPN's Whois Service
% you agree to abide by the following terms of use:
% http://www.ripn.net/about/servpol.html#3.2 (in Russian) 
% http://www.ripn.net/about/en/servpol.html#3.2 (in English).

domain:        LENTA.RU
nserver:       ns2.rambler.ru.
nserver:       ns3.rambler.ru.
nserver:       ns4.rambler.ru.
nserver:       ns5.rambler.ru.
state:         REGISTERED, DELEGATED, VERIFIED
org:           Rambler Internet Holdings, LLC
registrar:     RU-CENTER-REG-RIPN
admin-contact: https://www.nic.ru/whois
created:       1999.07.22
paid-till:     2013.08.01
free-date:     2013.09.01
source:        TCI

Last updated on 2013.04.02 23:01:36 MSK

Также, вы можете использовать PHP whois класс, который понимает даже рф зоны.

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