I have been studying for ccna off and on for 2 years while working as network admin for last 6 years. Decided to take test again and failed 770/825! I want to scream! i have been putting off learning more advanced features to focus on core of CCNA. Now debating its value. I do give up and move on with higher level features. I dont think that i can look at ccna material anymore.... Can anyone recommend good exam sims?