Fetch CNAME record of domain from PHP Code

It sounds like it's timing out.

Are your DNS servers reachable and fast? Is the CLI dig problematic/slow?

Are you able to write into the code a timeout value?

I have just found this:
http://stackoverflow.com/questions/3111227/why-wouldnt-dns-get-record-show-cnames-when-i-know-they-exist

I'm wondering if this would be related to your issue?

If you read the docs, you will probably come to the same conclusion that I have: This is an unreliable way to test for information because it relies on many factors that are outside of your control.
http://php.net/manual/en/function.dns-get-record.php

Can you please tell us the "50,000 foot view" of what you're trying to do?  What is the business problem that you're trying to solve?  Maybe there is a more reliable approach than querying foreign servers.

The platform we are rolling out sits on set subdomains. For example: sub1.domain.com :: sub2.domain.com :: sub3...

Now when a new customer comes we simply want to point customer1 to sub1.domain.com so it's ready to go instantly.

We seem to be able to achieve this but its not reliable - we have to refresh several times. It's off :: on

Are you wanting to route all new customers to their own individually chosen subdomains?   So if the customer is "ray" I would get "ray.domain.com" ?

Correct . .but to the "backed" you would get: sub1.domain.com

So you type: ray.domain.com :: and the code sees sub1.domain.com

Hmm... I don't know how to do that. Maybe .htaccess redirect?  It would be a research project for me.  BTW, this script never finds CNAME information on my server unless I use www. in the URL.  Then it finds some information in the return value.  You can try it here:
https://www.iconoun.com/demo/temp_starquest321.php

<?php // demo/temp_starquest321.php
/**
 * https://www.experts-exchange.com/questions/29022245/Fetch-CNAME-record-of-domain-from-PHP-Code.html
 *
 * http://php.net/manual/en/function.dns-get-record.php
 */
error_reporting(E_ALL);
echo '<pre>';


$hostname = $_SERVER['HTTP_HOST'];
$authns = [];
$addtl = [];
$info = dns_get_record( $hostname, DNS_ANY, $authns, $addtl );

var_dump('DNS_ANY', $hostname, $info, $authns, $addtl);


$authns = [];
$addtl = [];
$info = dns_get_record( $hostname, DNS_ALL, $authns, $addtl );

var_dump('DNS_ALL', $hostname, $info, $authns, $addtl);


$authns = [];
$addtl = [];
$info = dns_get_record( $hostname, DNS_CNAME, $authns, $addtl );

var_dump('DNS_CNAME', $hostname, $info, $authns, $addtl);

Select allOpen in new window