Preparing for Docker Certified Associate (DCA) Certification in 6 Weeks

"You've been using Docker for 2 years, but how can I verify your skill level?"

The recruiter's question hits like a cold shower. Thomas, a freelance DevOps engineer, masters Docker in production. He orchestrates Swarm clusters, handles midnight rollbacks, and optimizes images. But it's hard to concretely prove this expertise during an interview.

In a market where everyone "does Docker," standing out becomes a challenge. How do you show that you truly master Docker rather than just copying commands from Stack Overflow?

The Docker Certified Associate (DCA) certification addresses this issue. It goes beyond a simple line on your resume: it's concrete validation that places you in the top 15% of Docker professionals. According to feedback from certified professionals, there's a salary increase of 15 to 20% after obtaining it, along with enhanced credibility with recruiters.

The certification allows you to go from "using Docker" to "mastering Docker according to industry standards": commands, architectures, security, production best practices.

The good news? 6 well-organized weeks are enough to prepare. No need for a career break or thousands of dollars in training courses. With Train With Docker and the right resources, you can transform your field experience into recognized certification.

Docker Certified Associate Exam: Format, Price, and Registration#

The exam in numbers:

• 55 questions in 90 minutes (approximately 1min30 per question)
• $199 USD (administered by Mirantis Training)
• 2-year validity after obtaining
• Passing score: not officially published, aim for 70%+ to be safe
• Question types: Classic multiple choice + DOMC (40% of the exam)

The DOMC format: the main exam challenge#

DOMC stands for Discrete Option Multiple Choice. This format is what causes many candidates' scores to drop.

Unlike classic multiple-choice questions where you see all the answers, DOMC works differently:

• One option appears at a time
• You answer YES or NO immediately
• Impossible to go back
• You never know how many options remain

Let's take a concrete example. The exam asks: "Which methods expose a Docker Swarm service on an external port?"

• Option 1: --publish → Do you answer YES or NO?
• Option 2: docker service update --publish-add → YES or NO?
• Option 3: --mode global → YES or NO?

Impossible to compare answers with each other. Each option must be evaluated in isolation, which requires solid knowledge rather than an ability to eliminate wrong answers. This format effectively separates those who have truly practiced from those who have simply skimmed the documentation.

Questions are about real-world scenarios, not abstract theory. For example: "A container crashes with exit code 137. Which command do you use first to diagnose?" This is exactly the type of situation you encounter on a Tuesday evening when monitoring goes haywire.

Registering for the DCA exam#

1. Official website: Mirantis Training
2. Prerequisites: No degree required, Docker experience recommended
3. Proctored exam: Remote (webcam + online supervision)
4. Result: Immediate after the exam

Fortune 500 companies, scale-ups, and DevOps consulting firms immediately recognize the DCA certification. It proves you can architect, secure, and maintain Docker according to industry standards.

The 6 Domains of the Docker Certified Associate Exam#

The DCA exam evaluates your ability to solve real problems in six specific domains.

1. Orchestration (25%)#

This is the most important exam domain, with Docker Swarm and Kubernetes via Mirantis Kubernetes Engine (MKE).

Questions cover services, stacks, scaling, rolling updates in real production scenarios. For example: "Scale a service from three to ten replicas with zero downtime."

You need to know the difference between docker service scale and docker service update --replicas, two commands that seem similar but have different behaviors.

Since Mirantis maintains Docker Enterprise with MKE, the exam includes Kubernetes questions. You don't need to be a CKA expert, but you must understand basic workloads, services, and how MKE orchestrates everything.

I recommend dedicating 40% of your preparation time to this domain. A quarter of your exam is decided here.

2. Image & Registry (20%)#

Multi-stage builds, layer optimization, private registries, tagging strategies.

Typical question: "Reduce this image from 1.2GB to <300MB without losing functionality."

The classic trap? Believing that adding RUN apt-get clean on a new line optimizes your image. Docker layers don't work like that.

You really need to understand how Docker builds and caches layers, not just copy-paste Dockerfiles found on Medium or blindly trust what generative AI suggests.

3. Installation & Configuration (15%)#

Mirantis Kubernetes Engine (formerly UCP), Mirantis Secure Registry (formerly DTR), backup and disaster recovery strategies.

Questions are about enterprise scenarios like: "How do you properly backup MKE and MSR?" or "How do you backup Mirantis Secure Registry images?"

Even if you've never installed MKE/MSR in production (and few people have), you need to know the architecture, main components, and restoration procedures.

4. Networking (15%)#

Overlay networks, bridge, host mode, Docker embedded DNS, port publishing.

Typical question: "Two Swarm services run on different overlay networks. How do you connect them without recreating the services?"

The recurring trap: confusing --network which allows attaching a container to a network, and --publish which exposes a port to the outside.

DOMC questions on networking are particularly tricky because they force you to validate each network option in isolation, without being able to compare with others.

5. Security (15%)#

RBAC, Docker secrets vs configs, image scanning, principle of least privilege, content trust.

Typical question: "A compromised container is detected in your Swarm cluster. What's your first action?"

A classic trap: confusing secrets (encrypted sensitive data) and configs (non-sensitive configuration files). Both are managed via Swarm, but their use cases and security levels differ.

Questions test your ability to think like in production: identify vulnerabilities and apply enterprise best practices.

6. Storage & Volumes (10%)#

Persistent data, volume drivers, bind mounts vs volumes, tmpfs, data migrations.

Typical question: "Migrate data between two Swarm hosts without downtime. What strategy do you adopt?"

The trap: not knowing when to use tmpfs (temporary data in RAM) versus volumes (disk persistence).

Although this domain represents only 10% of the exam, questions are precise. Commands like docker volume inspect, docker volume ls --filter, and different mount options should be part of your knowledge.

Preparation time allocation:

• Orchestration: 40%
• Images & Registry: 25%
• Networking + Security + Installation: 30%
• Storage: 5%

Best Docker Labs to Prepare for DCA Certification#

Choosing the right tools makes the difference between effective preparation and weeks lost fighting technical problems.

Train With Docker: your turnkey solution#

The main advantage: preconfigured Docker/Swarm instances available with 1 click.

No more spending hours configuring three VMs that refuse to communicate with each other, or dealing with "it works on my machine but not the other" problems.

You connect, create a session, and can practice immediately. The integrated web interface allows working without any local installation.

The main asset for DCA preparation: the DOMC format and the ability to practice in real conditions.

You can read documentation for hours, but until you've practiced this format where each option appears in isolation and you must decide YES or NO without seeing what's next, you won't be truly ready on exam day.

Train With Docker lets you train in these real conditions from the beginning of your preparation.

One-hour sessions are renewable for free, allowing you to test the approach. If you like it, the premium version costs less than a Big Mac per month for full access. Compared to the exam cost ($199 USD), the investment is minimal.

Solution comparison#

Train With Docker offers the best value for 95% of candidates, from beginner to advanced intermediate level.

Official Docker documentation#

Docker documentation remains your absolute reference. But I advise against reading it cover to cover: you'll drop out around page 47 and lose several days.

Recommended strategy:

1. Use the official DCA Study Guide (free on the Mirantis site) as a checklist
2. Identify your knowledge gaps
3. Dive into corresponding documentation sections
4. Bookmark the 5 pages you consult most often

Community and study groups#

DCA certification preparation can feel solitary. Fortunately, DevOps communities are active and welcoming.

Reddit (r/docker and r/devops) for specific questions. You'll often find someone who has already encountered your exact problem with a stubborn overlay network, with complete debugging.

Discord and Slack DevOps communities for real-time exchanges. You ask a question in the afternoon, you generally get several responses within the hour.

GitHub awesome-docker for complementary resources. You'll find cheat sheets, automation scripts, and examples of complex Swarm stacks. Everything is open source and production-tested.

Preparing with a partner (someone also taking the exam) makes the experience less heavy and more effective: you challenge each other, compare your practice test scores, and explain concepts that pose problems.

6-Week DCA Preparation Plan#

6 weeks to go from "I know Docker" to "I'm DCA certified". Between 5 and 10 hours per week, well-structured, are generally enough.

The most effective approach: follow Train With Docker scenarios one by one, in the recommended order. They progressively cover the six exam domains.

"5 commands per day" technique#

Establish a daily ritual: each morning, before opening Slack or your emails, execute 5 Docker commands without consulting help:

• docker service create
• docker stack deploy
• docker node ls
• docker network inspect
• docker secret create

This ritual develops your muscle memory, which will be your best ally facing the DOMC format.

Tips for exam day#

A few points of attention for the exam:

Don't over-analyze questions that seem obvious. If a question seems simple, it probably really is.

With the DOMC format, your brain will sometimes suggest checking the first answers for safety. Resist this temptation and evaluate each option in isolation, as you practiced during your preparation.

Statistics show that candidates who modify their answers in the last 10 minutes are wrong more often than they correct themselves. Unless there's a blatant error, trust your first answers.

At the halfway point, take a 30-second break to breathe and close your eyes. This mental reset can make a difference on the second half of the exam.

Keep a water bottle within reach (mention it to the proctor at the beginning of the exam to avoid any misunderstanding).

After 6 weeks of structured preparation, having followed Train With Docker scenarios and practiced the DOMC format, you'll have seen all tested concepts. The exam shouldn't hold any major surprises.

70% correct answers are enough. You don't need perfection, just to demonstrate that you master Docker in production according to industry standards.

You now have all the keys to succeed in your DCA certification.