mod_geoip2 is the module that allows Apache to gather GeoIP data. You'll need GeoIP installed to use mod_geoip2.
Use your web browser to check out http://www.maxmind.com/download/geoip/api/mod_geoip2/ and find the latest version number. Copy the link so you can paste it into wget.
Done! apxs automatically enables it in the Apache config file for us (although we already did that above). If you run the following command you should see geoip_module listed in the module list.
Once we get PHP installed, you can use the following test script (inside a web page, this won't work from the command line) to see the GeoIP data in the $_SERVER global variable.
<?php
print_r($_SERVER);
?>