<?php

function domain_check($domain) {

$data = 'http://'.$domain;

// Create a curl handle to a non-existing location
$ch = curl_init($data);

// Execute
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_exec($ch);

// Check if any error occured
if(curl_errno($ch))
{
    return '<span style="color:#22c922">The domain is available!</span>';
} else {
    echo 'Curl error: ' . curl_error($ch)."<br />";
    return '<span style="color:#c92222">The domain is not available</span><br />';
    
}

// Close handle
curl_close($ch);
}

// Usage:
if(isset($_POST['domain'])) {
 echo domain_check($_POST['domain'].$_POST['tld']);
}

?>

<form method="POST" action="">
http:// <input type="text" name="domain" value="" />
<select name="tld">
<option value=".com">.com</option>
<option value=".net">.net</option>
<option value=".biz">.biz</option>
</option>
<input type="submit" value="Check">
</form>