Guys, I just want to inform you I failed again score 795. Before it was okay 812 but now I don't know what happen.

In troubleshooting 100
Operation and implementation 67
Tech 69
Can somebody help me? do I need to read the ICND??? I'm only using Cisco Intro and I Boson netsim 6.
And honestly I can already memorize what is in the book but I am wondering what went wrong

I'm confuse about what is inside the packet when bla bla bla sending to.
maybe I don't have experience in networking.
Or maybe I should stop dreaming.
Actually I am now planning to buy a kit of videos but I don't know if this one will work for me. Everyday I read the book 4 hours a day and subnetting I could rarely answer it in my head.
BUT Da__Mn WHAT went wrong I am?????
Well hope to hear your advice......
Good luck to all