Docker Certified Associate (DCA) case studies
DCA · Put your knowledge to work in context.
The Docker Certified Associate (DCA) is a professional credential for Docker container technologies, described by its awarding body as the first and only official certification program for Docker skills. It was created for practitioners working with the Docker Enterprise Edition platform in production, and the exam is designed to validate professionals with a minimum of 6 to 12 months of Docker experience. The DCA case studies are 5 cases and about 2,797 words.
1Disk pressure on a UCP worker with pending service tasks
A Docker Enterprise 3.0 cluster runs UCP 3.0.12 and DTR 2.7.8 on 12 nodes: three managers that also run workloads and nine dedicated workers. DTR has two replicas and stores images on a local volume on each replica.
604 words, about 3 min2Rolling update rollback caused by a missing health-check start period
A 20-replica service payments-api runs on a six-node Swarm in Docker EE 19.03. The service uses update config: parallelism: 4, delay: 10s, order: start-first, failure action: rollback, monitor: 30s .
571 words, about 3 min3Overlay MTU blackhole and an audit requirement for client IPs
A legacy billing application is being migrated to Docker EE 3.0 Swarm. It has two components: a frontend billing-web over HTTP and a backend billing-ledger that binds to UDP port 514 and must see the original client IP address for audit.
527 words, about 3 min4Unsigned images and vulnerable base images in a DTR/UCP pipeline
A regulated team runs Docker EE 3.0 with UCP and DTR 2.7. DTR has image scanning enabled and a policy that blocks deployment of images with critical vulnerabilities.
553 words, about 3 min5Swarm quorum loss after manager decommissioning
A Docker EE Swarm has five manager nodes and ten workers. During a maintenance window, an operator runs docker swarm leave --force on two managers that were being decommissioned, then reboots a third manager for kernel updates.
542 words, about 3 min