The pass-rate goal of the VCDX program is that every candidate who is accepted to defend passes. We have not yet achieved this goal. In my time as VCDX Program Manager, I have worked with a number of unsuccessful candidates. I have found that they tend to express similar concerns. This document collects these concerns, together with responses. I hope that it will help past candidates make constructive use of their experiences, and that it will help future candidates, including those reapplying, to succeed.
"Interestingly enough, all unsuccessful candidates' defense sessions vary, but successful candidates are remarkably similar. The candidate is comfortable answering all questions, no matter whether they're about the customer requirements, the logical design, or the physical design, jumping freely among them as needed. The candidate speaks crisply, without any unnecessary words. When the candidate doesn't know the answer to a question, he or she says immediately, "I don't know. But here's where I'd look to find the answer, and the consequences of that answer on my design would be X.""
^^^ That right there is the most important thing to keep in mind.
This is fantastic Brian. Thank you to yourself and VMware for putting it together.
Not to turn this into yet another scattered source of tips, but I'll add on one thing. A common theme can be categorized as "I think I am good enough". For all of the hard work that goes into the process, it's definitely a fair self assessment. However, this is where the 360 feedback is key. I performed several mock examinations prior to my defense to help prepare myself. The mock defenses don't necessarily need to be "in person" panelist style but it helps. I felt that I didn't really have anyone locally that I could lean on for mock exams so I conducted all of mine through email. Gracious friends stepped forward, took all the time to go through my design, and then drill me with questions. Again, I feel the results were very beneficial. Questions were asked which I wasn't quite prepared for. Great questions. An untold number of hours are spent preparing the design and reviewing it. But a valid assessment can't be completed in a vacuum. The exponentially increasing numbness to your own design yields a false sense of security. Peer review is an excellent reality check.
I'm glad y'all think this writeup is helpful. Here's another excellent question I got from a candidate.
The scenario I got for my design exercise was based on EMC storage. I am not an EMC guy, so this put me at a disadvantage.
All candidates have equal odds of getting scenarios involving network and storage gear from any major vendor. In spite of EMC's part-ownership of VMware, we are not biased in favor of EMC. (I should also mention that Cisco's and Intel's ownership stakes in VMware also don't affect VCDX scenarios.) In the past, I have seen scenarios involving IBM, HP, and NetApp storage too.
We have considered making all scenarios involve fictitious hardware, so that every candidate would be at an equal disadvantage. We might say "This customer uses Frammistan 2000 storage, and Nestle-brand routers and switches!" But frankly, the benefit of this fictionalization would be small. When in the real world you're confronted with storage you don't know, what questions do you ask? You ask whether it's iSCSI, FCoE, FC over fiber, or NAS; whether it's a high-end or low-end model; whether it's active-passive or active-active or supports ALUA; what it's capacity is; what kind of IOPS it can sustain; and so forth. You can do this quickly and efficiently in a VCDX defense session as well, and it doesn't count against you.
I should caution candidates that, even though it's not in the scoring rubric, most folks assume that VCDXes have an airline-magazine-level understanding of the storage and network markets. People assume that VCDXes know that NetApp loves NFS, that HP's high-end storage is called XP (and licensed from Hitachi), that EMC's big gun is the Symmetrix VMAX, and so forth, and that routers and switches are probably Cisco unless you hear otherwise. I should emphasize that none of that stuff is scored for. But having this kind of market awareness will make you more confident during your defense.
I can understant the except. But I think that a VCDX candidate must know (not necessary in the detail) most common networking and storage solutions.
I also got in my desing a specific hardware solution... but you do not need to be a specifical to understand how you can use it during the defense.
And the VCAP4-DCD (at least in the beta version) incuded some vendor specific questions.