PHP checkdnsrr() Function Usage and Example

PHP HTTP Reference Manual

The checkdnsrr() function performs DNS communication checks for the specified host (domain) or IP address

Syntax

bool checkdnsrr ( string $host [, string $type = "MX" ] )

Definition and Usage

It checks the DNS records of the corresponding host or IP address.

Parameters

Return Value

　If the record can be found, it returns TRUE; if the DNS record cannot be found or an error occurs, it returns FALSE.

Update Log

PHP 5.3.0　 -　　 This function can also be used on the Windows platform.
PHP 5.2.4　 -　　 Added TXT record type.
PHP 5.0.0 　 -　 Added AAAA record type.

Online Example

Try the following example

<?php
function validate_email($email){
　　　$exp = "^[a-z\'0-9]+([._-][a-z\'0-9]+)*@([a-z0-9]+([._-][a-z0-9]+))+$";
　　　if(eregi($exp,$email)){
　　　　　　if(checkdnsrr(array_pop(explode("@",$email)),"MX")){
　　　　　　　　return true;
　　　　　　}else{
　　　　　　　　return false;
　　　　　　}
　　　}else{
　　　　　　return false;
　　　}　　　　
}
?>

The following code checks if the password is valid

PHP HTTP Reference Manual