gethostbyname() gets IP address corresponding to the hostname
gethostbynamel() gets list of IP addresses corresponding to the hostname
gethostbyaddr() gets hostname corresponding to an IP address
getmxrr() fetches the mail exchange (MX) record associated with a hostname
dns_get_mx() alias for getmxrr()
checkdnsrr() checks for the existence of DNS records for a hostname
dns_check_record() alias for checkdnsrr()
dns_get_record() fetches DNS records associated with a hostname
$ip = gethostbyname ( "www.rntsoft.com" );
echo "IP = $ip\n";
$host = gethostbyaddr ( "192.0.34.166" );
echo "Host = $host\n";
$ip = gethostbynamel ( "yahoo.com" );
print_r ( $ip );
?>