Students often ask me what modules are in standard perl that they can be sure will be on every machine they want to deploy their code.
The only answer I can give them is not care about that but to prepare for installing things.
Not only that the list of core modules is changing from version to version of perl releases but it also depends on the downstream distribution they use.
On many systems perldoc is in a separate package and does not come with the main perl package.
I just found out that Red Hat also separates CPAN.pm into its own package so their standard perl does not even include CPAN.pm
