Whole document tree
6. Back up /etc and its subdirectories on one or more floppies.
This is the other extreme: you won't be restoring these files (for the most part, anyway); you'll be comparing them with the new ones that get created during installation. Why? Because the new ones may have data that the old ones didn't, or may express the old data in new ways. Changes in protocols, addition of new tools, or implementation of new features in existing tools may all dictate changes in the formats of the configuration files and startup scripts that the /etc tree contains, and you'll very likely have to edit your old data into these files so as to preserve the new formats and take advantage of the improvements.