The Fake CPAN is actually a collection of versioned, fake CPANs. A published fake CPAN version should never change. When an update is available, it will get a new URL. Starting with http://fakecpan.org/, fake CPAN URLs look like this:
http://fakecpan.org/fake/IDENTIFIER/VERSION/cpan
Each fake CPAN is part of a series with a unique identifier. An identifier is a bunch of words composed of letters and hyphens, matching the following Perl 5 regular expression:
/ \A (?:[a-z]+-)* [a-z]+ \z/x
The version part is determined by the fake CPAN series, but will follow the same semantics as a Perl $VERSION value. Putting it all together, the package index for v1.234 of the example series would be found at:
http://fakecpan.org/fake/example/v1.234/cpan/modules/02packages.details.txt.gz
The string latest may always be used in place of a version to reach the latest version of a given fake.
Each version contains all the files you expect:
modules/02packages.details.txt.gz modules/03modlist.data.gz authors/01mailrc.txt.gz authors/id/A/AU/AUTHOR/Dist-1.00.tar.gz ...
The following other resources are expected to exist:
http://fakecpan.org/fake/IDENTIFIER/VERSION/... about.txt - a description of the fake policy.txt - a description of how the contents may be expected to change over time (this helps users understand how to write test code that will be forward compatible)