php判断域名是否存在

<?php
function domainExists($domain) {
    if (gethostbyname($domain) !== false) {
        return true;
    } else {
        return false;
    }
}

$domain = "example.com";
if (domainExists($domain)) {
    echo "$domain exists.";
} else {
    echo "$domain does not exist.";
}
?>

<?php
function domainExists($domain) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $domain);
    curl_setopt($ch, CURLOPT_NOBODY, 1);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_exec($ch);
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    return $httpCode >= 200 && $httpCode < 300;
}

$domain = "example.com";
if (domainExists($domain)) {
    echo "$domain exists.";
} else {
    echo "$domain does not exist.";
}
?>