So you can find different modules in different categories like network, XML processing, CGI, database interface, and so on. I'd like to leverage all of this code to a new employer, so I set up a similar environment.
It would really help a lot to know which Linux distro your doing this project on. gethostbyaddr is a built-in Perl function that returns the hostname for a particular IP address. Their Instant Perl Modules|Douglas Sparling writers are also pretty cool. Start the Internet Information Services (IIS) Manager. If either (or both) of these come back with nothing, you'll need to do an upgrade/install as I mentioned above. Interestingly, there are many Perl modules available in the Comprehensive Perl Archive Network (CPAN). This directory would be used to store perl modules. apt-get install libThe CGI::Application module before 4.
Perl cgi module Introduction to Perl and CGI.