Docker Certified Associate Exam

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.

= Simultaneously creating and tagging multiple images is not an advantage of multi-stage builds.Multi-stage builds are a feature that allows you to use multiple FROM statements in your Dockerfile, each starting a new stage of the build1. You can selectively copy artifacts from one stage to another, leaving behind everything you don't want in the final image.This helps you to optimize the size and security of your images, as well as to simplify your build process12. However, multi-stage builds do not create or tag multiple images at once.Each Dockerfile produces one final image, which is the result of the last stage in the Dockerfile1.If you want to create and tag multiple images from a single Dockerfile, you need to use the--targetoption with thedocker buildcommand, and specify the name of the stage you want to build and tag3.Reference:

Multi-stage builds | Docker Docs

What Are Multi-Stage Docker Builds? - How-To Geek

Stop at a specific build stage | Docker Docs

The command kubectl drain <node name> is the correct one to run on the node to gracefully terminate all pods on the node, while marking the node as unschedulable. This command will safely evict all the pods from the node before you perform maintenance on the node, such as installing patches or an OS upgrade1. It will respect the PodDisruptionBudgets you have specified, if any, and allow the pod's containers to gracefully terminate1. It will also mark the node as unschedulable, so that no new pods can be scheduled on the node until it is ready1.

The other commands are not correct because:

* docker swarm leave will make the node leave the swarm cluster, but it will not affect the Kubernetes workloads on the node2.

* docker node update -availability drain <node name> will change the availability of the node to drain, which means that no new tasks can be assigned to the node, but it will not terminate the existing pods on the node3.

* kubectl cordon <node name> will mark the node as unschedulable, but it will not evict the pods on the node4.

* Safely Drain a Node | Kubernetes

* [docker swarm leave | Docker Docs]

* [docker node update | Docker Docs]

* [kubectl cordon | Kubernetes Docs]

: The networking drivers that allow you to enable multi-host network connectivity between containers are bridge, macvlan, ipvlan, and overlay. These drivers create networks that can span multiple Docker hosts, and therefore enable containers on different hosts to communicate with each other. The other drivers, such as host, user-defined, and none, create networks that are either isolated or limited to a single host. Here is a brief overview of each driver and how it supports multi-host networking:

* bridge: The bridge driver creates a network that connects containers on the same host using a Linux bridge. However, it can also be used to create a network that connects containers across multiple hosts using an external key-value store, such as Consul, Etcd, or ZooKeeper. This feature is deprecated and not recommended, as it requires manual configuration and has some limitations. The preferred driver for multi-host networking is overlay1.

* macvlan: The macvlan driver creates a network that assigns a MAC address to each container, making it appear as a physical device on the network. This allows the containers to communicate with other devices on the same network, regardless of the host they are running on. The macvlan driver can also use 802.1q trunking to create sub-interfaces and isolate traffic between different networks2.

* ipvlan: The ipvlan driver creates a network that assigns an IP address to each container, making it appear as a logical device on the network. This allows the containers to communicate with other devices on the same network, regardless of the host they are running on. The ipvlan driver can also use different modes, such as l2, l3, or l3s, to control the routing and isolation of traffic between different networks3.

* overlay: The overlay driver creates a network that connects multiple Docker daemons together using VXLAN tunnels. This allows the containers to communicate across different hosts, even if they are on different networks. The overlay driver also supports encryption, load balancing, and service discovery. The overlay driver is the default and recommended driver for multi-host networking, especially for Swarm services4.

* Use bridge networks

* Use macvlan networks

* Use ipvlan networks

* Use overlay networks

This does not configure a Docker container to export container logs to the logging solution. The docker logs command shows information about the logs of a container. It does not export or send the logs to any external destination. To configure a Docker container to export container logs to the logging solution, you need to use the --log-driver and --log-opt flags when creating or running the container. These flags allow you to specify which logging driver and options to use for the container. For example, to use Splunk as the logging driver, you can use --log-driver splunk and provide the Splunk URL, token, and other options using --log-opt. Reference: https://docs.docker.com/engine/reference/commandline/logs/, https://docs.docker.com/config/containers/logging/configure/, https://docs.docker.com/config/containers/logging/splunk/