How to check which apache modules are enabled/installed?

You're on Ubuntu so try:

apache2ctl -M

httpd -M will tell you which modules are built-in or shared.

Nothing from above answers works if you can’t run commands on remote server. If you have only “user” privileges or none at all try creating test.php script:

<pre>
<?php
print_r(apache_get_modules());
?>
</pre>

Though it will work only if PHP is installed as mod_php.