Deatheye on "php_network_getaddresses: getaddrinfo failed"

Hi
I was trying to run wordpress on IIS 8 PHP 5.4.X mySQL 5.2.x

Warning: mysql_connect(): php_network_getaddresses: getaddrinfo failed: No such host is known. in ...\wwwroot\wordpress\wp-includes\wp-db.php on line 1038

Warning: mysql_connect(): php_network_getaddresses: getaddrinfo failed: No such host is known. in ...\wwwroot\wordpress\wp-includes\wp-db.php on line 1038

The only things I found about this error seem to hint at DNS Resolution Errors or generell Access Problem to the database.

I've wrote a Little php scryipt manually that Access the DB and get's some data out of a table I created manually and put some data in there to test the Connection. The PHP file showed me the table data without a Problem using the same DB and user from the same Server, even put it in the same Directory where the wordpress files are.

Doesn't make a diffeerence if I put an IP or the host Name into the Connection configuration file.

I assume it's somehow a Problem with IIS8 or the PHP Installation Since ist also Happening with other applications I tried out.
Any Ideas where / what to look for?
The Webserver has 2 NICs, one for public Access and one for the internal Network that connects to the Database.