Today, I took the CWNA certification in order to keep my CWNT status up-to-date. I know what you're probably thinking: this guy co-authored the study guide, so re-certifying should be a walk in the park, right? Well, I didn't want to take anything for granted, so I spent a day or two sharpening up.
To prepare, I purchased a set of practice questions and ran through them all, read through the newest version of the CWNA slides, and re-read sections of the study guide that I was sure that I was weak on (like FHSS, which I don't run into very much).
I'm happy to say that I passed with an 85%.
Sometimes people post on here saying that the exam is unfair, that the study guide doesn't cover all of the material, or that the questions on the exam are ambiguous. Having seen two sets of practice questions and one set of test questions, I have to say that I think the test fulfills its purpose very well. I realize that my opinion might be taken as biased, given my association with Planet3, but keep in mind that I've been a professional instructor for over ten years, that I have participated in the development of two certification exams other than CWNA and that I have developed many classes, so my perspective on the effectiveness of study materials and certification exams comes from a much wider pool of experience than just CWNA.
My perspective is that the CWNA study materials are first and foremost designed to make you an excellent WLAN administrator. That means that there is some information in the class and in the study guide that is not tested, but that is still useful to an administrator.
My perspective is that the CWNA exam is first and foremost to test your knowledge and experienc with wireless LANs. That means that there are going to be some questions on the test that aren't explicitly covered in the study materials, BUT that a WLAN administrator with a certain level of experience will PROBABLY know. Now, granted, an experienced WLAN administrator probably won't know ALL of these questions, or maybe the administrator's experience leads him or her to a different answer than the test developer's experience, but that's why 70% is passing and not 100%. The administrator doesn't have to get every question right or agree with the developer in every case in order to pass.
Of course, many of the questions have deterministically correct answers, and study and memorization are necessary to get these right. One way that I can think of that people can improve their odds of passing is to make sure that they have memorized as much of the "book knowledge" as possible so that they have as much wiggle-room on the "experience" questions as possible. For example, one question on my test pertained to the frequencies used by 802.11 FHSS systems. If I hadn't looked that up the day before the test, I probably wouldn't have gotten it right. Taking the time to memorize that fact gave me one more chance to flub a more subjective question.
RF math is another good example. You should get every RF math question on the test right. Memorize the formulas and practice their application. The process of adding and subtracting dB and converting from dBm to mW is pretty straightforward. There is no subjectivity or judgement calls to it. If you walk into the test and you're not 100% confident in your ability to do RF math, you're throwing away points.
When all is said and done, I think that the CWNA test does a good job certifying that a candidate has a certain body of knowledge and experience. People who don't pass the CWNA test aren't dumb. They're not incompetent. They're potentially wonderfully proficient WLAN administrators. They're just not CWNAs.