EX188 Container Image Building Practice Test 4 — 15 Questions

Question 1

Which THREE advanced configuration steps or flags are available when performing rootless builds or utilizing buildah/podman build advanced features? (Choose three.)

Accepted Answer

Using '--tls-verify=false' to bypass TLS verification when pulling base images from insecure registries.. Advanced build features include custom storage, volume/secret mounts, and architecture specification.

Answer

Using '--rm=false' to automatically keep intermediate build container containers indefinitely on disk after successful builds.

Answer

Using '--privileged-build' to grant full root host capabilities to a rootless container build.

Question 2

Which THREE practices should be observed when managing environment variables (ENV vs ARG) in Containerfiles for secure and efficient builds? (Choose three.)

Accepted Answer

Use 'ENV' for configuration parameters that the application needs to read during container runtime.. ARG is build-time and doesn't persist, ENV persists into runtime, and sensitive values shouldn't be baked in.

Answer

Ensure that 'ENV' variables defined in earlier stages automatically carry over into subsequent multi-stage build stages without re-declaration.

Answer

Use 'ENV' for passing secret API tokens so they are automatically encrypted in the image layers.

Question 3

You are writing a Containerfile to build a custom application image using podman build. Which instruction should you use as the mandatory first non-comment instruction to define the base image?

Accepted Answer

FROM. The FROM instruction initializes a new build stage and sets the Base Image for subsequent instructions. Every valid Containerfile or Dockerfile must start with a FROM instruction.

Answer

IMPORT

Answer

BASE

Answer

INIT

Question 4

An administrator needs to execute a package update and install dependencies during the podman build process, ensuring these commands are committed as a new layer in the final image. Which instruction accomplishes this?

Accepted Answer

RUN. The RUN instruction executes any commands in a current layer on top of the current image and commits the results. The resulting committed image will be used for the next step in the Containerfile.

Answer

EXEC

Answer

START

Answer

CMD

Question 5

You need to copy local application source code from your build context into the /app directory inside the container image, automatically unpacking it if it is a local tar archive. Which instruction should you select?

Accepted Answer

ADD. The ADD instruction copies new files, directories, or remote file URLs from and adds them to the filesystem of the container at the path . A key feature distinguishing ADD from COPY is its ability to automatically extract local tar archives.

Answer

FETCH

Answer

TRANSFER

Answer

COPY

Question 6

By default, podman build executes build instructions using the root user. You want to switch the execution context to a non-privileged user named 'appuser' for all subsequent RUN, CMD, and ENTRYPOINT instructions. Which instruction should you use?

Accepted Answer

USER. The USER instruction sets the user name (or UID) and optionally the user group (or GID) to use when running the image and for any RUN, CMD and ENTRYPOINT instructions that follow it in the Containerfile.

Answer

LOGIN

Answer

SU

Answer

ACCOUNT

Question 7

You want to set the working directory for any subsequent RUN, CMD, ENTRYPOINT, COPY, and ADD instructions that follow it in the Containerfile. Which instruction achieves this?

Accepted Answer

WORKDIR. The WORKDIR instruction sets the working directory for any RUN, CMD, ENTRYPOINT, COPY, and ADD instruction that follows it in the Containerfile.

Answer

DIR

Answer

CD

Answer

PATH

Question 8

You are designing a container image that runs an executable web server. You want to provide default arguments to the executable that can be easily overridden by a user passing arguments directly to 'podman run'. Which instruction combination is best?

Accepted Answer

Use ENTRYPOINT for the binary and CMD for the default arguments.. ENTRYPOINT should define the executable, and CMD should define the default parameters that can be overridden easily when running the container.

Answer

Use ENV for the binary and WORKDIR for the arguments.

Answer

Use RUN for both the binary and the arguments.

Answer

Use CMD for the binary and ENTRYPOINT for the default arguments.

Question 9

You need to define a persistent environment variable named 'PORT' with the value '8080' that is available during both the build process and when running containers from the resulting image. Which instruction should you use?

Accepted Answer

ENV. The ENV instruction sets the environment variable to the value . This value will be persistent in the container when it runs and can also be referenced during build time.

Answer

SET

Answer

VAR

Answer

EXPORT

Question 10

An auditor reviewing your Containerfile notices an EXPOSE instruction for port 80. What is the primary function of the EXPOSE instruction?

Accepted Answer

It documents which ports the container listens on at runtime.. The EXPOSE instruction informs Podman that the container listens on the specified network ports at runtime. It functions as a type of documentation between the person who builds the image and the person who runs the container, though ports can still be published manually via flags.

Answer

It opens firewall ports on the underlying RHEL host system permanently.

Answer

It encrypts network traffic entering the specified container port.

Answer

It automatically publishes all exposed ports to random host ports without flags.

Question 11

You are optimizing a Containerfile using multi-stage builds to minimize image size. What is the key advantage of a multi-stage build in Podman?

Accepted Answer

It allows you to copy only finalized artifacts from a heavy build stage into a minimal production stage.. Multi-stage builds allow you to use multiple FROM instructions in a single Containerfile. Each FROM instruction starts a new stage with a different base, and you can copy artifacts from previous stages into the final stage, leaving behind build tools, compilers, and SDKs.

Answer

It automatically converts Dockerfiles into systemd service units.

Answer

It enables building container images concurrently across multiple remote container registries.

Answer

It eliminates the need for caching layers during the podman build process.

Question 12

Which TWO of the following instructions in a Containerfile can be written using either the shell form or the exec form?

Accepted Answer

RUN. Both RUN, CMD, and ENTRYPOINT support both shell form (e.g., RUN yum update) and exec form (e.g., RUN ["yum", "update"]). Among the options, RUN and CMD are standard examples.

Answer

WORKDIR

Answer

FROM

Answer

ENV

Question 13

Which THREE practices are recommended when optimizing cache utilization during image builds with podman build?

Accepted Answer

Place instructions that change frequently, such as COPYing source code, near the end of the Containerfile.. To maximize cache efficiency, place instructions that change frequently (like copying source code) lower down in the Containerfile, group related installation steps into single RUN commands, and order instructions from least frequently changed to most frequently changed.

Answer

Use the --no-cache flag on every routine build to ensure absolute freshness.

Answer

Always place COPY . . at the very top of the Containerfile before installing software dependencies.

Question 14

Which TWO instructions can be used to copy files or directories from a build context into a container image?

Accepted Answer

COPY. Both COPY and ADD can be used to copy files and directories from the build context into the container image filesystem.

Answer

PULL

Answer

INSTALL

Answer

GET

Question 15

Which THREE statements correctly describe the differences between CMD and ENTRYPOINT in a Containerfile?

Accepted Answer

Combining ENTRYPOINT and CMD allows default arguments to be supplied while retaining override flexibility.. ENTRYPOINT configures a container that will run as an executable; parameters in CMD can act as defaults or be overridden; and using exec form for ENTRYPOINT prevents container processes from receiving signals if not handled carefully, whereas shell form runs inside /bin/sh.

Answer

ENTRYPOINT instructions cannot be overridden at runtime under any circumstances.

Answer

CMD and ENTRYPOINT perform identical functions with no syntactical differences.