I actually thought I might have failed the exam, so I was very surprized to see that my score was 84%. That should tell you something about the difficulty of the questions. They are so poorly written that you can never be sure that
you got a question correct even if it is on a topic you studied thoroughly. But, luckily the most reasonable guess seems to usually be the correct answer. The test really doesn't go very deep into technical questions, but when it does,
it always manages to throw in an aspect of the topic that you wouldn't think was important enough to study carefully.
What makes this test so difficult is that almost every question asks for the 2 or 3 "most correct" answers and there are hardly any questions that are really straightforward, so it is very hard to tell how you are doing. Also, time is a big factor. I could not spend as much time on questions as I wanted to and finished with only 2 minutes left. I had marked 14 questions for review, but only had time to quickly look back at 3 of them. So, when the message popped up on the screen saying "Congratulations, You Passed!" I was both surprized and elated.
Here's how I prepared:
Professional XML 2nd Edition - Chapters 2-6, 8-12, 24, 27
XML Schemas - Chapters 1-9
XSLT - Chapters 1-8
The XSLT book is not necessary, in my opinion. The coverage of XSLT in PXML2 is very good and almost as deep as this book. The XML Schemas book is very good and was essential for me because I thought the coverage of XML Schemas in the PXML2 book was very poor.
I also did just about all the mock exams I could find, but none of them were even remotely similar to the style of questions on the real exam. However, they do help a little to get your mind into the mode of analyzing questions.
(Please do not waste your money on the WhizLabs exam. Not only are the questions way easy; it consists of a lot of true/false questions and there is not one true/false question on the real exam.)
So, the bottom line is that you have to study both broadly and deeply to have a chance at this exam. And then, it almost seems more like a reading comprehension test than a test of your XML knowledge. Although I think the exam is terribly written, I learned a lot about XML from my studies and am very happy with my passing score.