Centos – Installing PCNTL module for PHP without recompiling

Just install the package named php-xml, which provides the php-dom support.

You can find a list of downloads at http://rpm.pbone.net/index.php3/stat/4/idpl/10503222/com/php-xml-5.2.6-5.i386.rpm.html

Make sure to adjust configs in order to actually load the modules:

/etc/php.d/dom.ini
/etc/php.d/xmlreader.ini
/etc/php.d/xmlwriter.ini
/etc/php.d/xsl.ini

and restart apache.

The Apache functions are only available if running the httpd SAPI, also known as mod_php.

The stock CentOS PHP packages make mod_php available, so they are enough to allow them. If you need a newer version than the stock packages then you will need to find newer packages somewhere, or you will need to build PHP or the PHP packages yourself with the proper SAPI.