DCA Exam Dumps : Docker Certified Associate (DCA) Exam

The solution given is not a valid way to provide a configuration file to a container at runtime using Kubernetes tools and steps. The reason is that there is no such key as .spec.containers.configMounts in the PodSpec. The correct key to use is .spec.containers.volumeMounts, which specifies the volumes to mount into the container’s filesystem1. To use a ConfigMap as a volume source, one needs to create a ConfigMap object that contains the configuration file as a key-value pair, and then reference it in the .spec.volumes section of the PodSpec2. A ConfigMap is a Kubernetes API object that lets you store configuration data for other objects to use3. For example, to provide a nginx.conf file to a nginx container, one can do the following steps:

Create a ConfigMap from the nginx.conf file:

kubectl create configmap nginx-config --from-file=nginx.conf

Create a Pod that mounts the ConfigMap as a volume and uses it as the configuration file for the nginx container:

apiVersion: v1

kind: Pod

metadata:

name: nginx-pod

spec:

containers:

- name: nginx

image: nginx

volumeMounts:

- name: config-volume

mountPath: /etc/nginx/nginx.conf

subPath: nginx.conf

volumes:

- name: config-volume

configMap:

name: nginx-config

Configure a Pod to Use a Volume for Storage | Kubernetes

Configure a Pod to Use a ConfigMap | Kubernetes

ConfigMaps | Kubernetes

A Kubernetes node is allocated a /26 CIDR block (64 unique IPs) for its address space. This means that the node can assign up to 64 IP addresses to its resources, such as pods and containers. If every pod on this node has exactly two containers in it, then each pod will need two IP addresses, one for each container. Therefore, the node can support up to 32 pods, since 64 / 2 = 32. The other options are incorrect because they either exceed the available IP addresses or do not account for the number of containers per pod. References:

•CIDR Blocks and Container Engine for Kubernetes - Oracle

•How kubernetes assigns podCIDR for nodes? - Stack Overflow

= The pid namespace is not a Linux kernel namespace that is disabled by default and must be enabled at Docker engine runtime to be used. The pid namespace is one of the six namespaces that are enabled by default when you run a container with Docker1. The pid namespace isolates the process ID number space, meaning that processes in different pid namespaces can have the same PID2. This allows containers to have their own init process with PID 1 and to limit the visibility and interaction of processes between containers and the host3. To disable the pid namespace, you need to use the --pid option with the docker run command and specify the host or another container as the pid mode. References:

Docker run reference | Docker Docs

pid_namespaces(7) - Linux manual page - man7.org

Building containers by hand: The PID namespace - Enable Sysadmin

[Share host and container processes with --pid | Docker Docs]