Docker Updated DCA Exam Questions and Answers by rohan

While removing push access from all other users can prevent an image from being overwritten, it’s not the only way and might not be the most efficient or practical solution, especially in a collaborative environment. Docker Trusted Registry (DTR) provides a feature called ‘Immutable Tags’ which can be used to prevent an image, such as ‘nginx:latest’, from being overwritten. Once a tag is marked as immutable, DTR will prevent any user from pushing the same tag to the repository, thus preserving the image. This allows for better version control and prevents accidental overwrites. Therefore, the solution to prevent an image from being overwritten is not just to remove push access from all other users, but to use the features provided by DTR like ‘Immutable Tags’.

Docker Universal Control Plane (UCP) has its own built-in authentication mechanism and integrates with LDAP services1.It also has role-based access control (RBAC), so that you can control who can access and make changes to your cluster and applications1.However, there is no mention of Docker ID being a supported user authentication method for UCP in the resources provided1234.

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 theKubernetes Documentation on Network Policies.

= Storage is not a type of Linux kernel namespace that provides container isolation. Linux namespaces are a feature of the Linux kernel that partitions kernel resources such that one set of processes sees one set of resources while another set of processes sees a different set of resources1. The feature works by having the same namespace for a set of resources and processes, but those namespaces refer to distinct resources. Since kernel version 5.6, there are 8 kinds of namespaces: mount, UTS, IPC, PID, network, user, cgroup, and time2. Each kind of namespace isolates a different aspect of the system, such as file system mounts, host and domain names, inter-process communication, process IDs, network interfaces, user and group IDs, cgroups, and system time2. Storage is not one of them. References:

1: Linux namespaces - Wikipedia

2: Namespaces — The Linux Kernel documentation