Free Docker DCA Exam Actual Questions

The questions for DCA were last updated On May 1, 2024

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Question No. 1

You want to create a container that is reachable from its host's network.

Does this action accomplish this?

Solution: Use network attach to access the container on the bridge network.

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Correct Answer: A

Docker's bridge network allows containers connected to the same bridge network to communicate, while providing isolation from containers that aren't connected to that bridge network1. By using the network attach command, you can connect a container to the bridge network, making it reachable from the host's network12. However, it's important to note that containers on the default bridge network can only access each other by IP addresses, unless you use the --link option, which is considered legacy2. For better isolation and automatic DNS resolution between containers, it's recommended to use user-defined bridge networks12.


Question No. 2

Will this Linux kernel facility limit a Docker container's access to host resources, such as CPU or memory?

Solution: cgroups

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Correct Answer: A

Docker uses cgroups, a Linux kernel feature, to limit the resources a container can use. This includes CPU and memory resources12. For instance, Docker can limit a container's CPU usage to the equivalent of a single CPU core on the Docker host system2. Similarly, Docker can limit a container's memory usage1. However, to use these features, the Docker host must have cgroup memory and swap accounting enabled1. Therefore, cgroups can indeed limit a Docker container's access to host resources such as CPU and memory12.


Question No. 3

Will this configuration achieve fault tolerance for managers in a swarm?

Solution: one manager node for two worker nodes

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Correct Answer: B

Docker Swarm requires more than one manager node to achieve fault tolerance12. A single manager node is not fault tolerant because if it goes down, the entire cluster goes down3. For a swarm to be fault-tolerant, it needs to have an odd number of manager nodes2. For example, a three-manager swarm tolerates a maximum loss of one manager2. Therefore, a configuration with one manager node for two worker nodes will not achieve fault tolerance for managers in a swarm12.


Question No. 4

The Kubernetes yaml shown below describes a networkPolicy.

Will the networkPolicy BLOCK this trafftc?

Solution. a request issued from a pod bearing the tier: api label, to a pod bearing the tier: backend label

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Correct Answer: B

The provided Kubernetes NetworkPolicy YAML configuration indicates that the policy applies to pods with the label tier: backend in the default namespace1. The ingress rule allows traffic from pods with the label tier: api1. Therefore, a request issued from a pod bearing the tier: api label to a pod bearing the tier: backend label will not be blocked by this networkPolicy1. This is because the networkPolicy explicitly allows ingress from pods with the tier: api label1. For more information on Kubernetes Network


Question No. 5

The Kubernetes yaml shown below describes a networkPolicy.

Will the networkPolicy BLOCK this trafftc?

Solution. a request issued from a pod bearing only the tier: frontend label, to a pod bearing the tier: backend label

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Correct Answer: A

The provided Kubernetes NetworkPolicy YAML configuration indicates that the policy applies to pods with the label tier: backend in the default namespace1. The ingress rule allows traffic from pods with the label tier: api1. Therefore, a request issued from a pod bearing only the tier: frontend label to a pod bearing the tier: backend label will be blocked by this networkPolicy1. This is because the networkPolicy does not have a rule allowing ingress from pods with the tier: frontend label1. For more information on Kubernetes NetworkPolicies, you can refer to the Kubernetes Documentation on Network Policies.


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