Docker DCA - Certified Associate - Orchestration Image Creation Registry Networking Storage Security

By Morgan Lee · Updated Jul 10, 2026

Questions24
Passing Score75%
Format100% Multiple Choice
Sessions Logged1,683
Your progressLog in / Register to track times taken, best score, questions mastered, and coverage on this quiz.
Rating
4.6 (23)

Topics covered

This quiz

Uncategorized24 (100%)

Uncategorized24 questions

Browse more · Report this quiz

Question catalog for this preview

Catalog listing of the 5 preview questions for this quiz.

Question 1

A security team requires that containers run with read-only root filesystems to prevent unauthorized writes. A developer implements `docker run --read-only myapp` but the application fails because it needs to write to `/tmp`. What is the correct solution?

Answer choices

  • A. Remove `--read-only` for applications that need write access — it's incompatible with most applications

  • B. Add a `--tmpfs /tmp` mount — this provides an ephemeral, in-memory writable filesystem at `/tmp` while keeping the rest read-only

  • C. Mount a named volume at `/tmp` — this provides write access while maintaining root filesystem immutability

  • D. Set `--privileged` flag to allow writes to the read-only filesystem

Question 2

A developer runs `docker exec -it <container_id> bash` but receives the error `OCI runtime exec failed: container is not running`. What does this indicate?

Answer choices

  • A. The container is paused — run `docker unpause <container_id>` first

  • B. The container has stopped or exited — `docker exec` only works on running containers

  • C. The bash shell is not installed in the container image

  • D. The container needs `--interactive` flag at creation time to support exec

Question 3

A team is using Docker Swarm for container orchestration. They deploy a service with `docker service create --replicas 3 --name web nginx:latest`. One of the 3 nodes becomes unavailable. What does Docker Swarm do?

Answer choices

  • A. The service continues with only 2 replicas until the node recovers

  • B. Swarm's reconciliation loop detects the desired state (3 replicas) doesn't match the actual state (2 running) and schedules the missing replica on an available node

  • C. The entire service is stopped and must be manually redeployed

  • D. Swarm waits for the unavailable node to recover before rescheduling

Question 4

A developer creates a Docker network: `docker network create --driver overlay mynet`. Which statement about overlay networks is correct?

Answer choices

  • A. Overlay networks work only on a single Docker host

  • B. Overlay networks span multiple Docker Swarm nodes, enabling containers on different hosts to communicate using their container names as DNS hostnames

  • C. Overlay networks require a third-party network plugin like Calico or Flannel

  • D. Overlay networks replace the host network stack and require `--network=host` to be disabled

Question 5

A Docker Swarm service is deployed with `--update-parallelism 2 --update-delay 30s`. The service has 10 replicas and needs to be updated. Which statement describes the update behavior?

Answer choices

  • A. All 10 replicas are updated simultaneously with a 30-second total timeout

  • B. Updates occur in batches of 2 replicas, with a 30-second pause between each batch — total minimum update time is ~150 seconds for 10 replicas (5 batches × 30s)

  • C. 2 replicas are updated per minute (30-second delay means 2 per minute)

  • D. The update pauses after each batch until manual confirmation via `docker service update --continue`