Here is how to quickly check if domain is available...

I have seen the wildest answers to this question and would really hate to see some struggle with it.

Many solutions use a whois lookup which is very slow and in some cases could get your IP address temporarily banned.

My solution goes right at the source - for a domain to be registered it needs to have a NS (nameserver) record in the DNS so that it can be resolved to an IP address.

Here is an example that uses the is_domain_available function and finds the available domains from sports2000.com .. sports2099.com.

<pre>
<?php

// This is the key one
[B]function is_domain_available($domain)
{
  // quickly check for NS record
  return (count(dns_get_record($domain, DNS_NS)) == 0);
}[/B]

list($usec, $sec) = explode(' ', microtime());
$script_start = (float) $sec + (float) $usec;

for($i=0; $i<100; $i++)
{
  $domain = sprintf("sports2%03d.com", $i);
  if (is_domain_available($domain))
  {
    print "$domain is free!\n";
  }
}

list($usec, $sec) = explode(' ', microtime());
$script_end = (float) $sec + (float) $usec;

$elapsed_time = round($script_end - $script_start, 5);

print "Elapsed time: $elapsed_time\n";
?>
</pre>

Code (markup):

This function checked all 100 domains in 9 seconds.
I am open to suggestions/ideas on how to improve speed.

Has anyone tried connecting directly to OpenDNS servers?

 

..

++$i is faster than $i++
echo is faster than print
$domain = sprintf("sports2%03d.com", $i); is useless and slow..

 

silotka, thank you for the feedback!

The question I am really concerned about is how to speed up is_domain_available.

What is a good alternative for sprintf?

 

Thanks for the handy hack I will stash that in my library