Sometimes, it can be difficult to tell what modules are core, or even what modules are dualLived. For example, Term::ReadLine is part of the core, currrently 5.10.1; however, take a module like Module::CoreList. It's part of the core, but it is dualLived in that you can upgrade it without having to upgrade perl. I haven't found an easy way to determine if a module is dualLived, but you can use the corelist script from Module::CoreList to see if a module is indeed core. For an example from the command line:

corelist -a Term::ReadLine

An even better one:

 corelist -a /^Term::/

It'll return all the Term modules that are part of the core.