LWP::Online attempts to answer, as accurately as it can, one of the
nastiest technical questions there is:  Am I on the internet?

This a problem that had no clean permanent solution, and for
which you could just keep writing more and more functionality
indefinitely, asymtopically approaching 100% correctness but never
reaching it.

And so LWP::Online is intended to do as good a job as possible, without
having to resort to asking any human questions (who may well get it
wrong anyway), and limiting itself to a finite amount of programming
work and a reasonable level of memory overhead to load the code.

WWW: http://search.cpan.org/dist/LWP-Online/