EX188 Practice Test 2 — 10 Questions

Question 1

An administrator needs to attach to the terminal of a currently running container named backend_app to view its active console output interactively. Which command should be used?

Accepted Answer

podman attach backend_app. `podman attach` connects the current terminal's STDIN/STDOUT/STDERR to a running container's main process (PID 1), letting the administrator view live console output and interact with it. This is the direct equivalent of `docker attach` and is the correct tool for viewing an active console interactively.

Answer

podman console backend_app

Answer

podman connect backend_app

Answer

podman join backend_app

Question 2

Which TWO types of storage mechanisms are natively supported by Podman for container data persistence? (Choose two.)

Accepted Answer

Host bind mounts referencing directories on the host filesystem. Option B is correct because Podman natively supports host bind mounts, where a directory or file on the host filesystem is mapped directly into the container using the -v or --mount flag (e.g., -v /host/path:/container/path), making it a first-class persistence mechanism. Option D is correct because Podman also natively supports managed named volumes, which are created and tracked in Podman's own storage graph (typically under /var/lib/containers/storage/volumes for root or ~/.local/share/containers/storage/volumes for rootless users) and persist independently of container lifecycle. Option A is not a native Podman storage mechanism; NFS exports would have to be mounted on the host first and then exposed via a bind mount, and shared memory block devices are not a Podman persistence type. Option C is incorrect because direct Fibre Channel LUN mapping is a host-level storage concern handled by the OS, not something Podman natively provides to containers. Option E is incorrect because HDFS is a distributed filesystem service external to Podman and is not a natively supported container storage driver.

Answer

Shared memory block devices via NFS exports

Answer

Direct Fibre Channel LUN mapping inside containers

Answer

Distributed HDFS cluster mounts

Question 3

When writing a Containerfile, which instruction specifies the base image to be used for the subsequent build steps?

Accepted Answer

FROM. Every Containerfile must start with a FROM instruction to define the base image.

Answer

BASE

Answer

INIT

Answer

PARENT

Question 4

You are optimizing image build times and notice that a specific RUN instruction fetching dependencies is re-running on every build, even though the requirements.txt file has not changed. What is causing this behavior?

Accepted Answer

The COPY requirements.txt instruction was placed after an instruction that introduces non-deterministic data or the build context files have modified timestamps.. Docker/Podman layer caching invalidates a RUN layer when any preceding instruction's layer changes. If COPY requirements.txt comes after an instruction that produces non-deterministic output (e.g., a RUN that fetches latest packages or writes timestamps) or if build-context files have changed mtimes, the cache key for the COPY layer changes, invalidating all subsequent RUN layers including the dependency install.

Answer

The Containerfile lacks an explicit CACHE instruction at the top.

Answer

Podman disables caching by default for all RUN instructions containing package managers.

Answer

The USER instruction was set to root, which disables layer caching.

Question 5

An administrator wants to view a list of all running containers in a clean, tabular format without stopping containers or showing extra metadata. Which command should be used?

Accepted Answer

podman ps. podman ps lists running containers by default.

Answer

podman show running

Answer

podman list

Answer

podman containers

Question 6

You have created a Podman pod and want to launch two containers inside this pod so they share the same network namespace. How do you specify this during container creation?

Accepted Answer

podman run --pod mypod -d myimage. The --pod flag on podman run attaches a new container to an existing pod, and all containers in the same pod share the pod's network namespace (and by default its IPC and UTS namespaces). So podman run --pod mypod -d myimage launches the container inside the pod with shared networking. This is the standard way to add containers to a pod after the pod is created.

Answer

podman run --share-namespace mypod -d myimage

Answer

podman pod connect mypod myimage

Answer

podman run --network pod:mypod -d myimage

Question 7

A system administrator logs into a RHEL 9 server as a regular non-root user and executes 'podman ps'. The command succeeds, but no containers are displayed. What architecture feature enables this user to run containers without root privileges?

Accepted Answer

Linux user namespaces and subuid/subgid mapping. Rootless Podman relies on Linux user namespaces combined with subordinate UID/GID ranges defined in /etc/subuid and /etc/subgid. The user namespace maps the container's root (UID 0) to the unprivileged user's UID on the host, and additional container UIDs map into the allocated subuid/subgid ranges. This lets a non-root user run containers without any setuid daemon.

Answer

The Docker daemon running as a system service in user space

Answer

The systemd-logind setuid binary wrapper

Answer

SELinux multi-category security (MCS) translation tables

Question 8

An administrator needs to manage multiple containers simultaneously using Podman. Which THREE actions can be performed directly using Podman commands? (Choose THREE)

Accepted Answer

Stop all running containers using 'podman stop $(podman ps -q)'.. Option A is correct because 'podman stop $(podman ps -q)' uses command substitution: 'podman ps -q' returns the IDs of all running containers, and 'podman stop' then stops each of them in one command, enabling bulk management. Option D is correct because 'podman container prune' is a built-in Podman command that removes all stopped containers, which is a standard bulk cleanup action. Option E is correct because 'podman restart <container_name>' is a valid Podman command that restarts the specified container by name or ID. Option B is not valid because Podman has no 'podman edit --tag' command to directly edit a running container's image tag; image tags are managed with commands like 'podman tag' or 'podman build', not by editing a running container. Option C is not valid because Podman has no 'podman migrate' command to instantly move a running container to a remote physical server; container migration/checkpointing is handled by tools such as CRIU with 'podman container checkpoint' and 'podman container restore', not a simple 'migrate' subcommand.

Answer

Directly edit a running container's image tag using 'podman edit --tag'.

Answer

Instantly migrate a running container to a remote physical server using 'podman migrate'.

Question 9

An administrator needs to configure system-wide registry search shortcuts so that developers can run 'podman pull rhel9' and Podman automatically expands it to 'registry.access.redhat.com/rhel9'. Which configuration file and parameter accomplish this?

Accepted Answer

/etc/containers/registries.conf using the unqualified-search-registries parameter. The /etc/containers/registries.conf file contains the unqualified-search-registries parameter, which lists registries to search when a user pulls an image without specifying a registry. Adding registry.access.redhat.com to this list allows podman pull rhel9 to automatically expand to registry.access.redhat.com/rhel9.

Answer

/etc/sysconfig/podman using the SEARCH_REGISTRIES variable

Answer

/etc/containers/registries.d/default.yaml using the search-domains parameter

Answer

~/.config/containers/auth.json using the default-registry key

Question 10

A developer needs to optimize image size by removing build caches and temporary package manager cache files within the same RUN instruction. Why must this be done in a single RUN instruction?

Accepted Answer

Because file deletions in separate layers do not reduce the final image size due to the layered filesystem.. Container images are built as a stack of immutable layers, and each RUN instruction creates a new layer. If files are created in one RUN and deleted in a later RUN, the deletion only adds a whiteout marker in the new layer; the original files remain in the earlier layer and still contribute to the final image size. Performing installation and cleanup in a single RUN ensures the temporary files never persist in any committed layer.

Answer

Because package managers lock the database across different layers.

Answer

Because the container build engine will fail if cache cleanup happens in a separate layer.

Answer

To ensure environment variables persist between installation and cleanup.