Pretty sure you have to use sudo when on Centos, that's also true on Ubuntu which I just installed and configured for Perl.

Example: sudo cpan foo::bar

On Ubuntu 14.04 you would enter your user password, not the root password.

You also have to use sudo for apt-get when installing apps, or whatever Centos uses. Anyway I went with Centos at first, but it had little support and little help on the internet, so I went with Ubuntu and got it running.