PHP | checkdnsrr() Function

The checkdnsrr() function is an inbuilt function in PHP that is used to check the DNS records corresponding to the hostname or IP address. This function can be used to verify whether a domain name exists or not.

Syntax:

bool checkdnsrr( string $host, string $type )

Parameters: This function accepts two parameters as mentioned above and described below:  

• $host: It is required parameter. It specifies the host name or IP address which to be checked.
• $type: It is optional parameter. It specifies the type of DNS record to be checked. Its possible values are: A, AAAA, A6, ANY, CNAME, MX (default), NAPTR, NS, PTR, SOA, SRV, TXT.

Return Value: This function returns TRUE if records found, otherwise returns FALSE.

Note:

• This function is available for PHP 4.0.0 and newer version.
• On Windows platforms this function is available from PHP 5.3.0.

Below programs illustrate the checkdnsrr() function in PHP:

Program 1:

PHP

<?php

$domain = "geeksforgeeks.org";

if(checkdnsrr($domain, "MX")) {
    echo "Record exists.";
} else {
    echo "Record not found or error occurred.";
}
?>

Output:

Record exists.

Program 2:

PHP

<?php

$domain = "geeksforgeeks.org";

$arr = array(
    "A", "MX", "NS", "SOA",
    "PTR", "CNAME", "AAAA", "A6",
    "SRV", "NAPTR", "TXT", "ANY"
);

foreach( $arr as $element) {
    echo $element . ":";

    if(checkdnsrr($domain, $element)) {
        echo "found <br>";
    } else {
        echo "not found <br>";
    }
}

?>

Output:

A:found
MX:found
NS:found
SOA:found
PTR:found
CNAME:found
AAAA:found
A6:found
SRV:found
NAPTR:found
TXT:found
ANY:found

Reference: https://www.php.net/manual/en/function.checkdnsrr.php