Description:
------------
The return type of checkdnsrr and getmxrr are described as: Returns TRUE if any records are found; returns FALSE if no records were found or if an error occurred.

So if we check for a non-existant domain name, the result should be false.

The following command gives the expected result on my system, empty:
dig +short non-existant-domain-name.com MX

Bug found using Zend server 6.3, which is released with PHP 5.5.7. Also confirmed for current master.

Related to (closed) bug https://bugs.php.net/bug.php?id=8264

Test script:
---------------
Two test scripts:

php -r 'var_dump(checkdnsrr("non-existant-domain-name.com"));'
  bool(true)

php -r 'var_dump(getmxrr("non-existant-domain-name.com",$mxhosts));var_dump($mxhosts);'
  bool(true)
  array(0) {
  }


Expected result:
----------------
I would expect checkdnsrr("non-existant-domain-name.com") and getmxrr("non-existant-domain-name.com",$a) to return false.

Actual result:
--------------
They return true.

The case of getmxrr() is even stranger, this is the description of the meaning of the second parameter:
    A list of the MX records found is placed into the array mxhosts.

This list is empty! So the return type indicates there are records, but the second in/out argument indicates there are no records...