DCA Exam Dumps : Docker Certified Associate (DCA) Exam

 A DTR security scan will detect licenses for known third party binary components. This is because DTR security scan uses a database of vulnerabilities and licenses that is updated regularly from Docker Server1. DTR security scan can identify the components and versions of the software packages that are present in the image layers, and report any known vulnerabilities or licenses associated with them2. This can help users to comply with the licensing requirements and avoid potential legal issues3. References:

Set up vulnerability scans | Docker Docs

Scan images for vulnerabilities | Docker Docs

Container Security 101 — Scanning images for Vulnerabilities

 The command docker service create -name dns-cache -p 53:53 -service udp dns-cache is not valid because it has some syntax errors. The correct syntax for creating a swarm service is docker service create [OPTIONS] IMAGE [COMMAND] [ARG...]. The errors in the command are:

There should be a space between the option flag and the option value. For example, -name dns-cache should be -name dns-cache.

The option flag for specifying the service mode is -mode, not -service. For example, -service udp should be -mode udp.

The option flag for specifying the port mapping is --publish or -p, not -p. For example, -p 53:53 should be --publish 53:53.

The correct command for creating a swarm service that only listens on port 53 using the UDP protocol is:

docker service create --name dns-cache --publish 53:53/udp dns-cache

This command will create a service called dns-cache that uses the dns-cache image and exposes port 53 on both the host and the container using the UDP protocol.

[docker service create | Docker Documentation] : [Publish ports for services | Docker Documentation]

 SELinux could be blocking the operation of setting the system time from inside a Docker container. SELinux is a security mechanism that enforces mandatory accesscontrol (MAC) policies on Linux systems. It restricts the actions that processes can perform based on their security contexts, such as user, role, type, and level. By default, SELinux prevents Docker containers from accessing or modifying the host’s system time, as this could pose a security risk or cause inconsistency. To allow Docker containers to set the system time, SELinux needs to be configured with the appropriate permissions or labels, or disabled altogether. However, this is not recommended, as it could compromise the security and stability of the system. References:

Change system date time in Docker containers without impacting host

Change Date Inside a Docker Container

How to Handle Timezones in Docker Containers

5 ways to change time in Docker container

How to set system time dynamically in a Docker container