Docker DCA Exam With Confidence Using Practice Dumps

= Control Groups (cgroups) are a feature of the Linux kernel that allow you to limit the access processes and containers have to system resources such as CPU, memory, disk I/O, network, and so on1. Control groups allow Docker Engine to share available hardware resources to containers and optionally enforce limits and constraints2. For example, you can use the docker run command to specify the CPU shares, memory limit, or network bandwidth for a container3. By using cgroups, you can ensure that each container gets the resources it needs and prevent resource starvation or overcommitment4. References:

• Lab: Control Groups (cgroups) | dockerlabs
• Runtime metrics | Docker Docs
• Docker run reference | Docker Docs
• Docker resource management via Cgroups and systemd

The statement is incorrect because it does not mention the service name or the clusterIP address. Traffic sent to the IP of any pod with the label app: nginx on port 8080 will not be forwarded to port 80 in that pod, unless the traffic is coming from another pod within the same cluster that knows the pod IP. To access the service from outside the cluster, the traffic must be sent to the clusterIP address of the service, which is assigned by Kubernetes, and the port 8080 of the service, which is defined in the yaml file. The service will then forward the traffic to one of the selected pods on port 80.

To summarize, the correct statement should be:

Traffic sent to the clusterIP address of the service dca on port 8080 will be forwarded to port 80 in one of the pods with the label app: nginx.

Node taints are a way to mark nodes in a Swarm cluster so that they can repel or attract certain containers based on their tolerations. By applying node taints to the nodes that are designated for development or production, the company can ensure that only the containers that have the matching tolerations can be scheduled on those nodes. This way, the security policy requirements can be met. Node taints are expressed as key=value:effect, where the effect can be NoSchedule, PreferNoSchedule, or NoExecute. For example, to taint a node for development only, one can run:

kubectl taint nodes node1 env=dev:NoSchedule

This means that no container will be able to schedule onto node1 unless it has a toleration for the taint env=dev:NoSchedule. To add a toleration to a container, one can specify it in the PodSpec. For example:

tolerations:

- key: "env"

operator: "Equal"

value: "dev"

effect: "NoSchedule"

This toleration matches the taint on node1 and allows the container to be scheduled on it. References:

• Taints and Tolerations | Kubernetes
• Update the taints on one or more nodes in Kubernetes
• A Complete Guide to Kubernetes Taints & Tolerations