As tests go, not bad. It is very straightforward, no tricks, no fine print; just tests your network / Cisco knowledge. I took it and passed several years ago.
A kid that worked for me crammed for it, took it and failed. Crammed again, took it again, failed again. Did that several times and finally gave up. About 4 years later, after he had worked for me on networks all that time, took the test again without studying for it. Passed without any problems. Came back saying, "I don't know why I had so much trouble with it before. All the answers are just common sense." I think that is the best possible description I can give you.
The test is designed to keep you from memorizing 1,000,000 facts and passing the test without really knowing anything about networks. Try this for an example:
You understand addition and subtraction, so you don't need to memorize all the numbers between 1 and 100, you can just count by figuring out what the next number is using addition. Likewise you can count backwards from 100 to 1 by using subtraction and at about the same speed.
There is no formula with the alphabet, so you have memorized it and you can repeat the alphabet from A to Z very quickly because you have memorized it that way. Try repeating it backwards, from Z to A. Suddenly difficult and you may even have to work out the next letter by repeating to yourself from A to the next letter you need, over and over again? The difference between memorized items and really knowing how something works.