The answer is that the sysctl kernel.unprivileged_userns_clone must be set to 1, along with enabling user namespaces in the container runtime configuration and ensuring the container process does not require elevated host capabilities. This is correct because user namespaces map container UID/GID ranges to unprivileged host ranges, isolating the container from root on the host; without setting kernel.unprivileged_userns_clone to 1, the kernel blocks unprivileged user namespace creation entirely. On the CompTIA Linux+ XK0-005 exam, this tests your understanding of container security boundaries and namespace isolation, often appearing as a multi-select question where a common trap is confusing kernel parameters with runtime flags like --userns=host. Remember the mnemonic "Kernel First, Runtime Second"—the sysctl must be enabled before any runtime configuration can take effect.
XK0-005 Scripting, Containers and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers and automation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE conditions must be met for a Linux container to run with user namespaces enabled? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The container runtime must be configured to use user namespaces.
Option B is correct because user namespaces must be explicitly enabled in the container runtime configuration (e.g., `--userns=host` or `userns-remap` in Docker/Podman) to isolate the container's UID/GID mappings from the host. Without this configuration, the container will run in the default host namespace, negating the security benefits of user namespaces.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The container image must have a user with UID 0.
Why it's wrong here
User namespaces remap UIDs, so the image can have UID 0 mapped to an unprivileged host UID.
✓
The container runtime must be configured to use user namespaces.
Why this is correct
Docker requires --userns-remap to enable user namespaces.
Related concept
Read the scenario before looking for a memorised answer.
✓
The kernel must support user namespaces (CONFIG_USER_NS=y).
Why this is correct
Kernel support for user namespaces is required.
Related concept
Read the scenario before looking for a memorised answer.
✗
The container must be started with root privileges.
Why it's wrong here
User namespaces allow containers to run without root.
✓
The sysctl kernel.unprivileged_userns_clone must be set to 1.
Why this is correct
This enables unprivileged user namespace creation.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that a container must have UID 0 in its image or be started with root privileges to use user namespaces, when in fact user namespaces map an unprivileged host user to UID 0 inside the container.
Detailed technical explanation
How to think about this question
User namespaces work by mapping a range of unprivileged host UIDs/GIDs to UID 0 inside the container via `/proc/<pid>/uid_map` and `/proc/<pid>/gid_map`. The `kernel.unprivileged_userns_clone` sysctl (option E) is required on some distributions (e.g., older Ubuntu or RHEL) to allow unprivileged users to create user namespaces; without it, only root can create them, even if `CONFIG_USER_NS=y` is set.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
Scripting, Containers and Automation — This question tests Scripting, Containers and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The container runtime must be configured to use user namespaces. — Option B is correct because user namespaces must be explicitly enabled in the container runtime configuration (e.g., `--userns=host` or `userns-remap` in Docker/Podman) to isolate the container's UID/GID mappings from the host. Without this configuration, the container will run in the default host namespace, negating the security benefits of user namespaces.
What should I do if I get this XK0-005 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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