PHP/DNS/gethostbynamel

Retrieving All IPs Associated with a Domain

 
<?php
    $hostname = "google.ru";
    $ip_addrs = gethostbynamel($hostname);
    if(!$ip_addrs) {
        echo "Could not resolve the domain name $hostname<BR/>\n";
    } else {
        echo "Here is a list of IPs associated with $hostname:<BR/><BR/>\n\n";
        foreach($ip_addrs as $ip) {
            echo "IP: $ip<BR/>\n";
        }
    }
?>

Reverse Lookup of IPs Based on Domain

 
<?php
    $ip_addr = gethostbyname("www.google.ru");
    if($ip_addr ==="www.google.ru") {
        echo "Could not resolve the IP address for the host!<BR/>\n";
    } else {
        echo "The IP address for the host is: $ip_addr<BR/>\n";
    }
?>