305-300 Exam Dumps : LPIC-3: Virtualization and Containerization - Exam 305, version 3.0

The WORKDIR instruction sets the working directory for any subsequent RUN, CMD, ENTRYPOINT, COPY and ADD instructions that follow it in the Dockerfile1. The RUN instruction executes commands in a new layer on top of the current image and commits the results2. The RUN cd command does not change the working directory for the next RUN instruction, because each RUN command runs in a new shell and a new environment3. Therefore, the file test is created in the root directory (/) of the container image, not in the /tmp directory. References:

Dockerfile reference: WORKDIR

Dockerfile reference: RUN

difference between RUN cd and WORKDIR in Dockerfile

The purpose of a .dockerignore file is to specify files that Docker does not submit to the Docker daemon when building a Docker image. A .dockerignore file is a text file that contains a list of files or directories that should be excluded from the build context, which is the set of files and folders that are available for use in a Dockerfile. By using a .dockerignore file, you can avoid sending files or directories that are large, contain sensitive information, or are irrelevant to the Docker image to the daemon, which can improve the efficiency and security of the build process. The other options are incorrect because they do not describe the function of a .dockerignore file. Option A is wrong because a .dockerignore file does not affect the files existing in a Docker image, but only the files sent to the daemon during the build. Option C is wrong because a .dockerignore file does not exist in the root file system of containers, but in the same directory as the Dockerfile. Option D is wrong because a .dockerignore file does not affect the volumes that Docker attaches to a container, but only the files included in the build context. Option E is wrong because a .dockerignore file does not affect the parts of a Dockerfile that are executed, but only the files available for use in a Dockerfile. References:

What are .dockerignore files, and why you should use them?

Dockerfile reference | Docker Docs

How to use .dockerignore and its importance - Shisho Cloud

The correct command to boot a QEMU virtual machine using hardware virtualization extensions is qemu -accel kvm -drive file-debian.img -cdrom debian.iso -m 1024 -boot d. This command uses the -accel option to specify the hardware accelerator to use, which in this case is kvm. KVM is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V)1. The -drive option specifies the disk image file to use, which in this case is debian.img. The -cdrom option specifies the ISO image file to use as a CD-ROM, which in this case is debian.iso. The -m option specifies the amount of memory to allocate to the virtualmachine, which in this case is 1024 MB. The -boot option specifies the boot order, which in this case is d, meaning to boot from the CD-ROM first. References: