As day by day you lost track of your Apache configurations and Apache modules. Here is quick shell/bash command to check which modules are loaded and compiled with your current Apache version.
httpd -l
Output will be something like this:
Compiled in modules: core.c mod_authn_file.c mod_authn_default.c mod_authz_host.c mod_authz_groupfile.c mod_authz_user.c mod_authz_default.c mod_auth_basic.c mod_include.c mod_filter.c mod_deflate.c mod_log_config.c mod_logio.c mod_env.c mod_expires.c mod_headers.c mod_unique_id.c mod_setenvif.c mod_proxy.c mod_proxy_connect.c mod_proxy_ftp.c mod_proxy_http.c mod_proxy_ajp.c mod_proxy_balancer.c mod_ssl.c prefork.c http_core.c mod_mime.c mod_status.c mod_autoindex.c mod_asis.c mod_suexec.c mod_cgi.c mod_negotiation.c mod_dir.c mod_actions.c mod_speling.c mod_userdir.c mod_alias.c mod_rewrite.c mod_so.c
