Explanation
n: = Using the DTR web UI to make all tags in the repository immutable is not a good way to prevent an image, such as 'nginx:latest', from being overwritten by another user with push access to the repository. This is because making all tags immutable would prevent any updates to the images in the repository, which may not be desirable for some use cases. For example, if a user wants to push a new version of 'nginx:latest' with a security patch, they would not be able to do so if the tag is immutable. A better way to prevent an image from being overwritten by another user is to use the DTR webUI to create a promotion policy that restricts who can push to a specific tag or repository1. Alternatively, the user can also use the DTR API to create a webhook that triggers a custom action when an image is pushed to a repository2. References:
* Prevent tags from being overwritten | Docker Docs
* Create webhooks | Docker Docs

Explanation
A node is a physical or virtual machine running Docker Engine in swarm mode1. A node can be either a manager or a worker, depending on its role in the cluster1. A physical machine participating in the swarm is a node, regardless of its role or availability2. References:
* How nodes work | Docker Docs
* Manage nodes in a swarm | Docker Docs

The command docker network create -d overlay -o encrypted=true <network-name> will ensure that overlay traffic between service tasks is encrypted. This command creates an overlay network with the encryption option enabled, which means that Docker will create IPSEC tunnels between all the nodes where tasks are scheduled for services attached to the overlay network. These tunnels use the AES algorithm in GCM mode and manager nodes automatically rotate the keys every 12 hours1. This way, the data exchanged between containers on different nodes on the overlay network is secured. References:
* Overlay network driver

= The command kubectl events deployment api is not a valid kubectl command. The correct command to display the events for a deployment object is kubectl get events --field-selector involvedObject.name=api12.
This command uses a field selector to filter the events by the name of the involved object, which is the deployment called api. Alternatively, you can use kubectl describe deployment api to see the details and the events for the deployment3. References:
* 1: kubectl Cheat Sheet | Kubernetes
* 2: kubernetes - kubectl get events only for a pod - Stack Overflow
* 3: Kubectl: Get Events & Sort By Time - ShellHacks