Starting in 2006 (or even 2005, I can't remember anymore) with the VMware Certification Program, I got my first VCP certification with version 2, based on VMware Virtual Infrastructure 2.5 and vCenter 1.5. In these times, VMware was the only company that could offer a hypervisor for the enterprise class business.
During the following 8 (or 9) years, I refreshed VCP status for VCP3.5, 4 and finally version 5. VCP is now quite mainstream when you look at the numbers of VCPs out there (not to compare with Microsoft certified persons, this number is certainly much higher) and VMware decided to put another level of certification on top of VCP, called VCAP. The VCAP certification can be done in the DCA area (data center administration - more technical) or DCD area (data center design - more theoretical). As I see myself in the technical area, I decided to certify as VCAP-DCA to evolve to the next level of advanced VMware certifications.
I don't want to spent a lot of time explaining what VCAP-DCA is all about, you can get plenty of information for this if you ask your favorite search engine. If you do so, you will find many interesting and really helpful blogs and websites and you can get an idea of what you should know if you want to pass the test quite quickly (ignore the one with the proactive takings of pain killers, the exam isn't that hard :-) ).
To get to the basics, you need experience. Nothing will help you more than experience and hands-on practice. Sure you can grap the VCAP-DCA (or DCD) book from VMware press and it will tell you most of the information you need. BUT, this will never be enough because in the exam you are under time pressure. For me as a non-native english speaker the time frame is 240min for 26 labs. This sounds okay but it's not. The exam is based on real-life scenarios and 240min to solve 26 more or less difficult problems is hard even if you have hands-on experience. It is nearly impossible if you simply learned the topics from the book by heart. To make matters worst you work in a remote session that lags incredibly so using try-and-error is useless because you have to wait to long to see if your guess is correct or not. Second, you have an english keyboard layout (quite funny if you are used to german layout), third you are not allowed to take anything to drink or eat in the test room. You can drink but therefore you have to pause the exam and go outside but the clock will keep on ticking.
Using the VCAP-DCA preparation book is a good idea anyway. It will show you what you can expect during the exam and has some nice training scenarios. I'm not allowed to give any detailed information but some of the scenarios are quite similar to tasks I had to do in the real exam.
I think you have understood that you have to be well prepared for this exam.
To cut a long story short, I achieved today VCAP-DCA status despite the fact that I had much less time to prepare as I intended to spend. I was really happy to see the exam score flying in by email exactly 2h after I clicked on the "Finish exam" button in the test room so it seems, VMware is much faster as they think they are. They ask to be patient up to 15 business days until you get the score.