How to Pass the Apache Cassandra Administrator Exam (for Free!) in 2021

For a limited time, you may try (and retry) DataStax Academy’s Cassandra Administrator exam for free, and get a valuable Apache Cassandra Administrator Associate certification. Here is all about these newly reviewed certification and exam, including some practice tests I recommend to improve your chances and score higher.

About the Cassandra Administrator Certification

DataStax is the largest distributor of a commercial version for Apache Cassandra. Its DataStax Enterprise (DSE) includes core open source Cassandra, and it is free for developers working on smaller workloads. The new DataStax Astra is a cloud version you may try for free as well.

DataStax offered Cassandra Administrator exams and certifications for years. In mid-2020, with the reviewed Admin and Dev certifications for Cassandra 3 and DataStax Enterprise 6, they also changed their proctored provider to Mercer Mettl, a small firm from India.

The price for a Cassandra Administrator exam used to be $300 US or more. Right now, the listed price is at $145 US. But DataStax is running a huge special, that can help you pass this exam for free. Here is how…

About the Administrator Path Courses

• They call “Administrator Path” three DataStax Academy courses that you must watch, to be able to ask for a free voucher, and try pass the Cassandra Administrator exam for free. The courses are in fact several hours long videos, with quizzes and labs that require practicing by yourself, on your own installation of Cassandra:
  • DS101 – Introduction (30 minutes).
  • DS201 – Foundations (6 hours), mostly about Architecture.
  • DS210 – Operations (9 hours).
• You cannot watch their videos in high-speed, at your own pace. But they published them as well on YouTube. You’ll still have to zip-zip through their on-site videos, to mark each segment “complete”.
• Quizzes are great to quickly check if you properly understood the last video segment, but don’t rely on their format for the exam: the Cassandra Administrator exam questions are more elaborate and scenario-like. Quizzes must be also completed for the Admin path, with a score decent enough (don’t worry, they do not expect it 100%).
• Labs may help of course, but they are not required for the exam. If you do not have time enough, or if you don’t have a computer powerful enough to support their use cases, you can stick to the theory and this could do it.
• Once you complete these courses, send an email to [email protected] and ask them for a free voucher. They will send you a coupon code in no time. You may use it to try the Cassandra Administrator exam for free for the first time, or even to retry it again if you fail once! Here is how your dashboard should look once you complete all courses:

About the Cassandra Administrator Exam

• No need to schedule the exam, because there are proctors online anytime 24/7.
• Start the exam from your Mettl dashboard. When asked for a payment, enter your coupon code (if you have one) and you’re no longer sent to PayPal. Otherwise, the exam costs $145 US.
• The proctored exam is through a Chrome add-on that will take over your screen, with your consent.
• They take your picture and need a photo ID – all this through your laptop camera, if you have nothing better.
• The exam will start right away after. There are a total of 60 questions, mostly single-select with four choices each. No True/False, but 4-5 multi-select questions, where they tell you how many valid answers you must check.
• You have 90 minutes max, that could go fast because of the large number of questions. Find your pace and don’t waste too much time on them: better mark for later review any question for which you have doubts.
• The passing score is 70%. This means you can get max 18 questions wrong. It may look easy, but it is not: many questions are tricky, problem-solving, touching multiple aspects, and it is easy to miss a point. If you leave for review the questions you’re not sure about, this will give you a nice estimate by the end if you’re good or not.
• You may get an email right away after you finish the exam: they will tell you if you failed or passed, and with what score. If you passed, you’ll find a verification link in your Mercer Mettl dashboard, with your Cassandra Administrator exam sheet (they don’t tell you which questions you got wrong). You may download your certificate in PDF format as well, here is mine:

What the Administrator Exam Covered (or not)

Things you absolutely need to know for the actual exam:

• Architecture and Internals – you need deep understanding of compaction and compaction strategies, snitch and gossip, read repairs, hints and hinted handoff, nodes and vnodes etc.
• Replication Factor (RF) and Consistency Levels (CL) – typical scenarios with RF for multiple data centers, and R/W operations with specific CL.
• Read/Write Path – with MemTables and SSTables, read repairs and all internal data structures.
• Configuration Options and Files – learn most important settings and the files you need to look into. Make a difference between Cassandra and Java-related options.
• Adding, Removing and Replacing nodes – this is a main task for a Cassandra Administrator, so learn in detail all possible scenarios.
• nodetool and dsbulk – these are the most important tools, learn as much as you can about them.

Things I didn’t really expect in the exam:

• CQL – a lot of Cassandra Query Language, which was included more in the Developer path, and the Data Modeling course. You need to know both the proper syntax (to understand the examples), and the tricky parts – of batches and DML statements in particular. Understand “upserts” with INSERT or UPDATE, and how they work (or not) in applied/unapplied batches, or as lightweight transactions. You’ll get several scenario-based questions – learn both the CQL syntax and the tricky specific use cases. (No secondary indexes or materialized views – that’s just for Devs).
• Keys and Multi-row partitions – learn everything about the primary, partition and clustering keys. You’ll be asked to determine keys, and properly recognize what role each kind of key has. When a query may return a row, a partition, multiple rows from one or multiple partitions. Make sure you properly understand that by adding clustering keys, you likely switch to a multi-row partition. This part was also heavily included in the Developer path, as Data Modeling.
• Hybrid/Multi-Cloud Deployments – a new topic I do not remember from the learning path – you may get some questions about this.

Things I’ve been surprised the exam didn’t cover too much (sometimes not at all):

• generic NoSQL vs RDBMS
• specific DSE and Cassandra features
• tools like SSTable utilities, Cassandra Stress, OpsCenter or CQL COPY
• backups
• RBAC CQL commands (for users, roles, or permissions) and SSL certificates

About the Practice Tests

• In your Mercer Mettl dashboard you can try 20 questions they offer for free in an interactive practice exam. The level of detail and difficulty, and the way they are conceived, is the closest to your actual exam questions. All 20 questions are also discussed in detail – with answers and explanations – in this PDF you can download here. Or you can subscribe and wait for a 2-hour workshop they have monthly. Beware the test includes a few questions only for Devs, or only for Admins, from the following courses:
  • DS201 (Foundations) – 10 questions on CQL + 3 questions on Architecture.
  • DS220 (Data Modeling) – 2 questions for Devs only (you don’t need these as Admin).
  • DS210 (Operations) – 5 questions for Admins only.

• From these practice test questions for Admins, from my previous practice tests for the Developer exam, or inspired from both the actual exam and the courses from the Administrator path, I created two high-quality exam practice tests, with 60 questions each (just like the actual exam) that you can check on Udemy – FREE for next three days only with this link to Become a Certified Cassandra Administrator: Practice Exams. I’m not aware of any other material (interactive or not) that could help you better to pass the Cassandra Administrator exam. Here is an original exam-like question sample:

• Or you can opt-out for the alternative book you can take with you on an iPhone or iPad – look for Apache Cassandra Administrator Associate: Exam Practice Tests, in Kindle or paperback edition. It has the exact same practice tests and questions, except it is not interactive. But each practice test is divided into a printed section with all the questions, followed by a section with explained answers and external references for each question. Here is an example of question with a partial answer on an iPad:

Conclusion

• Apache Cassandra is the most popular NoSQL wide-column store, and such a certification can help your Administrator career.
• The running special that DataStax offers, to help you pass this proctored certification exam for free, is truly a unique opportunity: use it now, as it may not last forever.
• The exam is challenging enough, but fair: scenario-based questions are rather fun, and can show if you had real-life use cases to solve.
• Recommended courses do not fully prepare you for the format the exam questions present. The courses are great to teach you about Cassandra (Architecture and Operations), but the exam itself is a marathon of 60 questions you must be quick to solve.
• Learn more about Data Modeling and CQL, as you will need both, and most of these are included only in the Developer path. You need to be able to properly determine partition, cluster and primary keys, and understand how they can lead to single or multi-row partitions. Study also DML operations and batches in particular, as you will get some tricky scenario-based questions with them.
• Use my 2 practice tests, each with 60 original exam-like questions, with explanations and references, to increase your success chances at the exam and get a better score!