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 will check if the password is valid

PHP HTTP 　reference manual