What are common files on a web server that can be misconfigured and provide useful information for a hacker such as verbose error messages?

httpd.conf is the Apache HTTP Server configuration file that controls server-level settings like directory permissions and modules, but it does not directly control application-level error message verbosity in the way php.ini does.

administration.config is not a standard, commonly recognized web server configuration file and is not associated with a specific web technology's error reporting or verbose output settings.

php.ini is the main configuration file for PHP and contains directives such as 'display_errors' and 'error_reporting' that, when misconfigured (e.g., display_errors = On in a production environment), expose verbose error messages revealing file paths, database structures, and application logic to attackers. This makes it a high-value target for reconnaissance, as misconfigurations can inadvertently leak stack traces, SQL queries, and server internals. It is one of the most commonly misconfigured files on PHP-based web servers.

idq.dll is a Windows IIS component associated with the Index Server ISAPI extension and is known for a historical buffer overflow vulnerability (MS01-033), not for being a misconfigured file that produces verbose error messages.