What are some common limitations or restrictions imposed by domain registrars on Whois queries, and how can PHP scripts work around them?

Domain registrars often impose limitations on the number of Whois queries that can be made within a certain time frame to prevent abuse. To work around this limitation in PHP scripts, you can implement a delay between each query to stay within the allowed limit. 

<?php
$domain = 'example.com';
$whois_server = 'whois.verisign-grs.com';
$whois_port = 43;

$fp = fsockopen($whois_server, $whois_port, $errno, $errstr, 10);
if (!$fp) {
    echo "Error: $errstr ($errno)\n";
} else {
    fputs($fp, $domain . "\r\n");
    $response = '';
    while (!feof($fp)) {
        $response .= fgets($fp, 128);
    }
    fclose($fp);
    echo $response;
    
    // Add a delay to prevent exceeding query limits
    sleep(1);
}
?>

Keywords

Whois queries domain registrars limitations restrictions PHP scripts

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