I agree with Dimo. I failed it my first time simply because I was making the same mistake in Binary conversion on all the subnetting questions. One week later, after studying my mistake, I passed. Subnetting is key.
Also, if you don't already or plan to work in a Network related position, you might want to go another route. I find a lot of people taking the test to improve their resume, that is nice, but you will quickly learn from it.
I am now in a senior level position, and I don't work on routers and switches every day. The knowledge is helpful, but you need to work with Cisco on a day to day basis to stay sharp. I am now faced with trying to pass one of the CCNP exams to continue + renew my CCNA.
I think the Cisco certs are great to have, but most important is the knowledge and skills you will develop hands on. If I could do it again, I would go back and start entry level in a comms group or something. These days I am crunching Domino, Netscreen, Windows, and anything they throw my way, except ROUTING and SWITCHING!

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Anyway, good luck and I hope this was helpful.
John Judge
MCSE, MCSA, MCP, CCNA, CNA, Network +, A+