Use apache2ctl -M or httpd -M to list loaded apache modules.
The output will look similar to:
$ sudo apache2ctl -M Loaded Modules: core_module (static) log_config_module (static) logio_module (static) mpm_worker_module (static) http_module (static) so_module (static) alias_module (shared) auth_basic_module (shared) authn_file_module (shared) authz_default_module (shared) authz_groupfile_module (shared) authz_host_module (shared) authz_user_module (shared) autoindex_module (shared) cgid_module (shared) deflate_module (shared) dir_module (shared) env_module (shared) mime_module (shared) negotiation_module (shared) reqtimeout_module (shared) setenvif_module (shared) status_module (shared) Syntax OK
Cool!
