He has a slow link, and so he uses the CD as an incomplete local mirror, only fetching a module from another mirror if the version on the CD isn't the most recent. (For anyone who might have a similar problem, there's an answer in the CPANPLUS FAQ on how to set this up with CPANPLUS.)

And CPAN.pm does this by default as well. Put the http: URL first, and the file: URL later, and it'll automatically get the indicies from the first URL, but look at all file: URLs first for supplying the actual files, falling back to the first URL only if it cannot be gotten "locally". It's quite slick (and documented {grin}).

-- Randal L. Schwartz, Perl hacker