As I posted in here, I've just passed my LPI 101 exam.
I know it's not Sun, but generally I'd say that its worthwhile knowing all the caveats of certain commands and principles. A lot of its basic stuff, but you'll find some "trick" questions in the exam designed to catch you out. The best way around this is to read the question very carefully.
I did notice a couple of errors within the questions in the LPI exam, which wasn't very good form. i.e.
What directive indicates what fonts are available to X in the XF86Config file?
The answer was, of course, FontPath "unix/:7100" but the question was incorrect, as it doesn't indicate what fonts are available, it indicates that a font server is running locally and it should look there for its fonts.
So also be logical - if a question seems ambiguous, then look at the answers and remove those that are obviously incorrect.