The best resource in terms for ccna is the free boson simulator or the net visualizer simulator just to start with if you are looking for something free but i would never subsitute it for a real live cisco device where one can practise and learn alot because the simulator has bugs and limitations . Original cisco books that comes while doing the course for ccna is great and is very well laid out .
( Cisco CCNA Practice Test ) -> free ccna tests
if any help is needed please get in touch with me on this id stjude_1984@hotmail.com
Ya know, we prolly need a sticky for links to cert practice tests, study guides, etc. Unless they are somewhere else and I just haven't gotten around to bothering to look for them on here.