There are several ways to find out if mod_perl is enabled in your version of Apache. In older versions of Apache (versions earlier than 1.3.6), you could check by running httpd -v, but that no longer works. Now you should use httpd -l.
It is not enough to know that mod_perl is installed—the server needs to be configured for mod_perl as well. Refer to Chapter 4 to learn about mod_perl configuration.