To check the CPAN configuration (Current)

Type

sudo cpan

cpan>o conf

Will list the config

To set Mirrors to pick from, use this command

o conf init connect_to_internet_ok urllist

If you do not wish to get a list of mirrors and would prefer to set
your urllist manually, use just this command instead

o conf init urllist

Ubuntu problem with CPAN Perl

Most of us are facing problem when we are trying to install Perl packages from CPAN in Ubuntu
(this arises due to the fact that the installations are missing libraries which in turn required for make and build)

Try these steps and it will resolve the problem

sudo apt-get install build-essential

This will ask you to insert ubuntu CD into your CD/DVD drive. Insert it.

Then
sudo apt-get install libc6-dev

will download and install dev package.

then

sudo apt-get install libssl-dev
will be required when you are trying to install Crypt::SSLeay etc.

Now you try sudo cpan
install (Package you wish to install)

I hope these steps will help you the most.